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 A153487 #6 Sep 04 2014 14:18:04 %S A153487 3,17,265,4329,16779497,4311714025,73031059689,1152921577101035753, %T A153487 1329227995784915873480267885077956841, %U A153487 95780971304118054976624684827067692545766545852041449 %N A153487 Sum of first n perfect numbers A000396, divided by 2. %C A153487 Partial sums of A133028. [From _R. J. Mathar_, Jan 21 2009] %F A153487 a(n) = A092336(n)/2. %t A153487 Accumulate[(# (#+1))/2&/@Select[2^Range[90]-1,PrimeQ] ]/2 (* _Harvey P. Dale_, Sep 04 2014 *) %Y A153487 Cf. A000396, A092336, A153474, A153475, A153476. %K A153487 nonn %O A153487 1,1 %A A153487 _Omar E. Pol_, Dec 27 2008 %E A153487 More terms from _R. J. Mathar_, Jan 21 2009