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A057159 Numbers n such that n divides s(n-1), where s(1) = 1, s(n) = s(n-1) + (n+1)*3^n. 1

%I

%S 4,13,35,52,95,119,169,676,11596,57577,159484,276773

%N Numbers n such that n divides s(n-1), where s(1) = 1, s(n) = s(n-1) + (n+1)*3^n.

%C No other terms below 300000. - _Vaclav Kotesovec_, May 05 2018

%C s(n) = 1, 28, 136, 541, 1999, 7102, 24598,... 4*s(n) = 3^(n+1)*(2n+1)-23, with g.f. x*(-1-21*x+45*x^2) / ( (x-1)*(-1+3*x)^2 ). - _R. J. Mathar_, May 05 2018

%t seq = RecurrenceTable[{s[n] == s[n - 1] + (n + 1)*3^n, s[1] == 1}, s, {n, 1, 20000}]; Select[Range[1, Length[seq]], Divisible[seq[[# - 1]], #] &] (* _Vaclav Kotesovec_, May 05 2018 *)

%K nonn,more

%O 1,1

%A _Robert G. Wilson v_, Sep 13 2000

%E Minor edits by _Altug Alkan_, May 05 2018

%E a(10)-a(12) from _Vaclav Kotesovec_, May 05 2018

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Last modified January 23 07:07 EST 2020. Contains 331168 sequences. (Running on oeis4.)