This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A378998 #11 Dec 19 2024 10:08:11 %S A378998 1,2,0,3,0,0,0,4,1,0,0,0,0,0,0,5,0,3,0,0,0,0,0,0,5,0,0,0,0,0,0,6,0,0, %T A378998 0,2,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0, %U A378998 0,0,0,2,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 %N A378998 Number of trailing 1-bits in the binary representation of sigma(n). %H A378998 Antti Karttunen, <a href="/A378998/b378998.txt">Table of n, a(n) for n = 1..100000</a> %H A378998 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>. %H A378998 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>. %F A378998 a(n) = A007814(A088580(n)). [the 2-adic valuation of 1+sigma(n)] %F A378998 For all n in A028982, a(n) = A337195(n). %t A378998 IntegerExponent[DivisorSigma[1, Range[100]] + 1, 2] (* _Paolo Xausa_, Dec 19 2024 *) %o A378998 (PARI) A378998(n) = valuation(sigma(n)+1,2); %Y A378998 Cf. A000203, A007814, A088580, A028982 (positions of terms > 0), A028983 (of 0's), A072461 (of 1's), A072462 (of terms > 1), A337195, A378999 [= a(n^2)]. %K A378998 nonn %O A378998 1,2 %A A378998 _Antti Karttunen_, Dec 16 2024