|
%I #25 Sep 08 2022 08:46:06
%S 1,2,3,4,8,9,15,16,27,32,35,64,75,81,99,128,135,243,255,256,375,455,
%T 512,539,675,729,783,875,1024,1089,1215,1295,1715,1859,1875,2048,2115,
%U 2187,2375,2703,2975,3375,3519,4096,4335,4355,5375,5915,6075,6479,6561,6723
%N Numbers n such that p-1 divides n+1 for every prime divisor p of n.
%C Numbers of the form 2^k, k >= 0, and 3*5^m, m >= 0, are terms. - _Marius A. Burtea_, Oct 02 2019
%H Amiram Eldar, <a href="/A231811/b231811.txt">Table of n, a(n) for n = 1..10000</a>
%t fa = FactorInteger; Gu[n_] := Union@Table[IntegerQ[(n + 1)/(fa[n][[i, 1]] - 1)], {i, Length[fa[n]]}]; Select[Range[20000], Gu[#] == {True} &]
%o (PARI) isok(n) = {my(f=factor(n)[,1]); for (k=1, #f~, if ((n+1) % (f[k]-1), return(0));); return(1);} \\ _Michel Marcus_, Oct 02 2019
%o (Magma) [1] cat [k: k in [2..7000]| #[p:p in PrimeDivisors(k)| IsIntegral((k+1)/(p-1))] eq #PrimeDivisors(k)]; // _Marius A. Burtea_, Oct 02 2019
%Y Cf. A231810.
%K nonn
%O 1,2
%A _José María Grau Ribas_, Jan 20 2014
%E Term 1 prepended by _Max Alekseyev_, Jan 20 2014
|
