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 A105086 #15 Dec 10 2019 20:48:49 %S A105086 1,1,5,1,10,1,13,10,16,1,26,1,22,21,29,1,37,1,40,29,34,1,58,26,40,37, %T A105086 54,1,70,1,61,45,52,43,89,1,58,53,88,1,94,1,82,75,70,1,122,50,91,69, %U A105086 96,1,118,67,118,77,88,1,166,1,94,101,125,79,142,1,124,93,142,1,193,1,112 %N A105086 Sum of the divisors of n minus the least nontrivial proper divisor of n. %C A105086 a(n) = 1 iff n is prime. %H A105086 Charles R Greathouse IV, <a href="/A105086/b105086.txt">Table of n, a(n) for n = 2..10000</a> %F A105086 a(n) = sigma(n) - least nontrivial proper divisor(n). %F A105086 a(n) = A000203(n) - A020639(n), n >= 2. - _Omar E. Pol_, Dec 08 2019 %e A105086 a(6) = 10 because sigma(6) = 1 + 2 + 3 + 6 = 12, least nontrivial proper divisor(6) = 2 and their difference is 10. %t A105086 a[n_] := DivisorSigma[1, n] - Divisors[n][[2]] %o A105086 (PARI) a(n)=sigma(n) - divisors(n)[2] \\ _Charles R Greathouse IV_, Dec 10 2019 %Y A105086 Cf. A000203, A020639. %K A105086 nonn %O A105086 2,3 %A A105086 Toby Donaldson (tjd(AT)sfu.ca), Apr 07 2005 %E A105086 Edited and extended by _Robert G. Wilson v_, Apr 08 2005 %E A105086 Offset changed by _Charles R Greathouse IV_, Dec 10 2019