A332459 - OEIS

%I #8 Feb 16 2020 17:36:30

%S 1,1,5,1,7,13,9,1,7,19,13,29,15,25,25,1,19,5,21,43,33,37,25,61,1,43,

%T 41,57,31,73,33,1,49,55,49,23,39,61,57,91,43,97,45,85,79,73,49,125,29,

%U 47,73,99,55,121,73,121,81,91,61,169,63,97,105,1,85,145,69,127,97,145,73,49,75,115,125,141,97,169,81,187,61,127

%N Odd part of 1+sigma(n).

%H Antti Karttunen, <a href="/A332459/b332459.txt">Table of n, a(n) for n = 1..16384</a>

%H Antti Karttunen, <a href="/A332459/a332459.txt">Data supplement: n, a(n) computed for n = 1..65537</a>

%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%F a(n) = A000265(A088580(n)) = A000265(1+sigma(n)).

%F A002487(a(n)) = A324294(n).

%F a(2^n) = 0 for all n >= 0. [Zero occurs at least also at a(25). See A202274]

%o (PARI) A332459(n) = { my(s=1+sigma(n)); (s>>valuation(s,2)); };

%Y Cf. A000203, A000265, A002487, A088580, A161942, A202274, A324294, A332454, A332455.

%K nonn

%O 1,3

%A _Antti Karttunen_, Feb 16 2020