A329891 - OEIS

%I #17 Dec 11 2019 20:11:05

%S 0,1,1,4,0,24,-8,104,-48,352,80,1424,-2480,8736,2048,16384,-7008,

%T 111456,-80384,473600,-427008,1630976,750592,5731232,-12709664,

%U 36894720,12300416,68246368,-38345568,459223232,-401666240,2015330304,-862152384,5535523520,4631692288,21015756800,-61319782400,165674113600,46426506688,279934140416,-484569911296

%N a(0) = 0, a(1) = 1, for n > 1, a(n) = 2^n - (sigma((2^n)-1) - sigma((2^(n-1))-1)).

%H Antti Karttunen, <a href="/A329891/b329891.txt">Table of n, a(n) for n = 0..255</a>

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

%F a(0) = 0; for n >= 1, a(n) = A323244(2^n) - A323244(2^(n-1)) = 2^n - A329890(n).

%F a(n) = A329644(2^n).

%o (PARI) A329891(n) = if(n<=1,n,(2^n - sigma((2^n)-1)) + sigma((2^(n-1))-1));

%Y Row 1 of A329637.

%Y Cf. A000203, A000225, A075708, A156552, A323243, A323244, A329644, A329890, A329892.

%K sign

%O 0,4

%A _Antti Karttunen_, Nov 23 2019