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 A288349 #16 Jun 20 2017 23:14:21 %S A288349 1,2,4,5,7,11,12,14,18,26,27,29,33,41,57,58,60,64,72,88,120,121,123, %T A288349 127,135,151,183,247,248,250,254,262,278,310,374,502,503,505,509,517, %U A288349 533,565,629,757,1013,1014,1016,1020,1028,1044,1076,1140,1268,1524,2036 %N A288349 Partial sums of A059268. %F A288349 a(n) = 2^t + 2^(n-t*(t-1)/2) - t - 2, where t = floor(sqrt(2*n) + 1/2), n>=1. %e A288349 For n=10, a(10) = 1 + 1 + 2 + 1 + 2 + 4 + 1 + 2 + 4 + 8 = 26. %t A288349 Accumulate@ Flatten@ Array[2^Range[0, #] &, 10, 0] (* _Michael De Vlieger_, Jun 11 2017 *) %o A288349 (PARI) for(n=1, 100, t=floor(sqrt(2*n)+1/2); print1(2^t+2^(n-t*(t-1)/2)-t-2, ", ")); %Y A288349 Cf. A059268. %K A288349 nonn %O A288349 1,2 %A A288349 _Zhining Yang_, Jun 08 2017