A275478 - OEIS

%I #24 Aug 13 2023 16:52:50

%S 0,0,1,3,0,1,0,1,4,2,0,3,0,0,7,5,0,1,0,3,0,1,0,4,7,0,3,2,0,8,0,6,0,0,

%T 2,6,0,0,0,1,0,7,0,0,23,3,0,5,0,1,2,3,0,1,0,5,0,1,0,9,0,2,9,7,0,2,0,2,

%U 0,3,0,7,0,2,0,3,0,5,0,5,178,1,0,8,0,0,0,4,0,24,1,2,0,0,0,6,0,0,20,9

%N Least k such that d(n) divides d(n+2^k) (d = A000005).

%C a(225) > 300, if it exists. - _Antti Karttunen_, Jun 13 2023

%H Antti Karttunen, <a href="/A275478/b275478.txt">Table of n, a(n) for n = 1..224</a>

%F a(A057922(n)) = 0. - _Michel Marcus_, Aug 01 2016

%e a(45) = 23 because A000005(45) = 6 divides A000005(45+2^23) = 18.

%t A275478[n_]:=Module[{d=DivisorSigma[0,n],k=-1},While[!Divisible[DivisorSigma[0,n+2^++k],d]];k];Array[A275478,50] (* _Paolo Xausa_, Aug 13 2023 *)

%o (PARI) a(n) = {my(k = 0); while(numdiv(n+2^k) % numdiv(n) != 0, k++); k; }

%Y Cf. A000005, A057922, A275473, A275479.

%K nonn

%O 1,4

%A _Altug Alkan_, Jul 29 2016

%E Data section extended up to a(100) by _Antti Karttunen_, Mar 02 2023