A074696 - OEIS

A074696

Numbers k such that 2^k+1 has more than k divisors (k such that A000005(2^k+1) > k).

%I #17 May 10 2022 10:03:36

%S 0,1,30,42,45,50,54,63,70,75,78,81,90,99,102,105,114,118,126,130,135,

%T 138,150,153,154,162,165,168,170,171,174,175,177,180,182,186,189,190,

%U 194,195,196,198,204,210,216,220,222,225,228,230,231,234,238

%N Numbers k such that 2^k+1 has more than k divisors (k such that A000005(2^k+1) > k).

%H Amiram Eldar, <a href="/A074696/b074696.txt">Table of n, a(n) for n = 1..441</a>

%t Select[Range[0, 150], DivisorSigma[0, 2^#+1] > # &] (* _Amiram Eldar_, May 10 2022 *)

%o (PARI) isok(n) = numdiv(2^n+1) > n; \\ _Michel Marcus_, Nov 29 2013

%Y Cf. A000005, A046798.

%K nonn

%O 1,3

%A _Benoit Cloitre_, Sep 03 2002

%E More terms from _Michel Marcus_, Nov 29 2013

%E a(1) = 0 inserted by _Amiram Eldar_, May 10 2022