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 A173455 #12 Oct 30 2017 17:57:20 %S A173455 1,1,1,3,1,6,1,7,4,8,1,16,1,10,9,15,1,21,1,22,11,14,1,36,6,16,13,28,1, %T A173455 42,1,31,15,20,13,55,1,22,17,50,1,54,1,40,33,26,1,76,8,43,21,46,1,66, %U A173455 17,64,23,32,1,108,1,34,41,63,19,78,1,58,27,74,1,123,1,40,49,64,19,90,1,106 %N A173455 Row sums of triangle A027751. %C A173455 Essentially the same as A001065, but with a(1)=1. %C A173455 Note that if n is a noncomposite number then a(n)=1. %H A173455 Antti Karttunen, <a href="/A173455/b173455.txt">Table of n, a(n) for n = 1..4096</a> %t A173455 Array[Boole[# == 1] + DivisorSigma[1, #] - # &, 80] (* _Michael De Vlieger_, Oct 30 2017 *) %o A173455 (PARI) a(n) = if (n==1, 1, sigma(n) - n); \\ _Michel Marcus_, Oct 30 2017 %Y A173455 Cf. A001065, A008578, A027751. %K A173455 nonn %O A173455 1,4 %A A173455 _Omar E. Pol_, Nov 22 2010