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A014865 Numbers k that divide s(k), where s(1)=1, s(j)=15*s(j-1)+j. 1

%I

%S 1,3,5,7,15,21,35,49,55,105,147,165,245,343,385,605,723,735,903,915,

%T 1029,1155,1715,1815,2401,2485,2695,3615,3685,4235,4515,5061,5145,

%U 6321,6405,6655,7203,7455,8085,10065,11055,12005,12705,16807,17395

%N Numbers k that divide s(k), where s(1)=1, s(j)=15*s(j-1)+j.

%C Conjecture: all terms are odd, all terms greater than 7 are composite, and all terms greater than 1 are divisible by 3 or 5 or 7 some combination therof. - _Harvey P. Dale_, Dec 04 2020

%H Harvey P. Dale, <a href="/A014865/b014865.txt">Table of n, a(n) for n = 1..100</a>

%t nxt[{n_,a_}]:={n+1,15a+n+1}; Select[NestList[nxt,{1,1},17500],Divisible[ #[[2]],#[[1]]]&][[All,1]] (* _Harvey P. Dale_, Dec 04 2020 *)

%K nonn

%O 1,2

%A _N. J. A. Sloane_, _Olivier GĂ©rard_

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Last modified August 1 05:51 EDT 2021. Contains 346384 sequences. (Running on oeis4.)