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 A387424 #12 Sep 02 2025 14:08:48
%S A387424 0,1,2,4,6,6,8,11,14,16,19,21,23,25,27,31,33,34,37,38,41,44,48,51,54,
%T A387424 58,62,62,64,68,72,77,82,87,92,96,98,103,108,111,113,118,121,124,128,
%U A387424 132,137,141,145,150,155,158,160,164,169,172,177,182,185,190,192,196,200,206,211,215,218,224,230,234,238,244
%N A387424 Partial sums of A387423.
%H A387424 Antti Karttunen, <a href="/A387424/b387424.txt">Table of n, a(n) for n = 1..65537</a>
%H A387424 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>.
%H A387424 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>.
%F A387424 a(1) = 0; for n > 1, a(n) = a(n-1) + A387423(n).
%o A387424 (PARI)
%o A387424 up_to = 65537;
%o A387424 A387423(n) = { my(a=binary(n), b=binary(sigma(n)), i=1); while(i<=#a,if(a[i]!=b[i],return(#a-(i-1))); i++); (0); };
%o A387424 A387424list(up_to) = { my(v=vector(up_to)); v[1] = 0; for(n=2,up_to,v[n] = v[n-1]+A387423(n)); (v); };
%o A387424 v387424 = A387424list(up_to);
%o A387424 A387424(n) = v387424[n];
%Y A387424 Cf. A000203, A387423.
%Y A387424 Cf. also A387425.
%K A387424 nonn,base,new
%O A387424 1,3
%A A387424 _Antti Karttunen_, Sep 01 2025