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 A347121 #13 Oct 16 2021 15:21:22
%S A347121 -1,1,2,11,2,28,4,49,31,40,2,128,4,62,66,179,2,209,4,188,102,76,6,472,
%T A347121 59,98,218,286,2,420,6,601,126,112,146,859,4,134,162,700,2,636,4,368,
%U A347121 498,168,6,1592,149,445,186,466,6,1252,178,1058,222,184,2,1704,6,216,756,1931,230,828,4,548,278,940,2,3041,6
%N A347121 a(n) = A347136(n) - 2*n.
%H A347121 Antti Karttunen, <a href="/A347121/b347121.txt">Table of n, a(n) for n = 1..10000</a>
%H A347121 <a href="/index/Pri#gaps">Index entries for primes, gaps between</a>
%H A347121 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%F A347121 a(n) = A347136(n) - 2*n.
%F A347121 a(A000040(n)) = A001223(n).
%o A347121 (PARI)
%o A347121 A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
%o A347121 A347121(n) = (sumdiv(n,d,d*A003961(n/d))-(2*n));
%Y A347121 Cf. A000040, A001223, A003961, A347136, A347122 (Möbius transform).
%Y A347121 Cf. also A341512, A346239, A347236.
%K A347121 sign
%O A347121 1,3
%A A347121 _Antti Karttunen_, Aug 24 2021