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 A172522 #3 Mar 30 2012 18:40:50
%S A172522 6,18,36,56,77,101,131,167,207,249,297,351,411,474,540,612,690,770,
%T A172522 854,944,1040,1140,1242,1347,1455,1565,1679,1799,1925,2057,2193,2331,
%U A172522 2471,2615,2762,2912,3067,3223,3383,3545,3713,3887,4067,4253,4442,4634,4832
%N A172522 Partial sums of A049094.
%C A172522 The subsequence of primes in this sequence begins: 101, 131, 167, 3067.
%F A172522 a(n) = SUM[i=1..n] {i such that 2^i - 1 is divisible by a square}.
%e A172522 a(20) = 6 + 12 + 18 + 20 + 21 + 24 + 30 + 36 + 40 + 42 + 48 + 54 + 60 + 63 + 66 + 72 + 78 + 80 + 84 + 90.
%Y A172522 Cf. A000040, A014491, A049093, A049096, A049095, A001220.
%K A172522 nonn
%O A172522 1,1
%A A172522 _Jonathan Vos Post_, Feb 06 2010
%E A172522 More terms from _R. J. Mathar_, Feb 16 2010