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A178796
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An ascending sequence of primes a(n) such that either the sum of decimal digits of a(n) is divisible by the sum of decimal digits of a(n+1) or vice versa.
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3
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2, 11, 13, 17, 31, 53, 71, 79, 97, 101, 103, 107, 211, 233, 251, 277, 349, 367, 431, 439, 457, 503, 521, 547, 619, 673, 691, 701, 709, 727, 853, 907, 1021, 1061, 1069, 1087, 1151, 1201, 1223, 1249, 1429, 1447, 1483, 1511, 1601, 1609, 1627, 1663, 1753, 1861, 1933, 1951, 2011, 2099
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OFFSET
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1,1
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..1000
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EXAMPLE
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The sums of the digits of a(n) form the sequence d(n) = 2, 2, 4, 8, 4, 8, 8, 16, ... in which either d(n)/d(n+1) or d(n+1)/d(n) is an integer.
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MAPLE
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A178796 := proc(n) option remember; if n = 1 then 2; else a := nextprime(procname(n-1)) ; while true do r := A007953(a)/ A007953(procname(n-1)) ; if numer(r) = 1 or denom(r) = 1 then return a; end if; a := nextprime(a) ; end do: end if; end proc:
seq(A178796(n), n=1..80) ; # R. J. Mathar, Jun 28 2010
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MATHEMATICA
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nxt[n_]:=Module[{k=NextPrime[n], tidn=Total[IntegerDigits[n]]}, While[ !Divisible[ Total[ IntegerDigits[ k]], tidn] && !Divisible[ tidn, Total[ IntegerDigits[k]]], k=NextPrime[k]]; k]; NestList[nxt, 2, 60] (* Harvey P. Dale, Aug 23 2017 *)
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CROSSREFS
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Different from A068807.
Sequence in context: A079132 A184802 A023257 * A068807 A241732 A154812
Adjacent sequences: A178793 A178794 A178795 * A178797 A178798 A178799
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KEYWORD
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base,nonn
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AUTHOR
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Giovanni Teofilatto, Jun 15 2010
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EXTENSIONS
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Corrected by Giovanni Teofilatto, Jun 25 2010
Definition corrected, sequence extended, example added by R. J. Mathar, Jun 28 2010
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STATUS
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approved
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