%I #7 Aug 18 2024 14:46:27

%S 1,3,4,16,8,72,24,304,160,944,624,6576,-544,14336,16384,72544,19616,

%T 342528,50688,1475584,466176,3443712,2657376,29486880,-3340288,

%U 54808448,65971360,306781024,77647680,1475408064,132153344,5157119680,3054411072,12548176896,13343981568,130039259136,-28235160128,228451400256,269821673472

%N a(1) = 1; for n > 1, a(n) = sigma((2^n)-1) - sigma((2^(n-1))-1), where sigma is A000203, the sum of divisors.

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

%F a(1) = 1; and for n > 1, a(n) = A075708(n) - A075708(n-1).

%t Join[{1},Table[DivisorSigma[1,2^n-1]-DivisorSigma[1,2^(n-1)-1],{n,2,40}]] (* _Harvey P. Dale_, Aug 18 2024 *)

%o (PARI) A329890(n) = if(1==n,1,sigma((2^n)-1)-sigma((2^(n-1))-1));

%Y From second term onwards, the first differences of A075708.

%Y Cf. A000203, A329637, A329891, A329892.

%K sign

%O 1,2

%A _Antti Karttunen_, Dec 08 2019