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 A300671 #8 Feb 11 2021 11:19:52 %S A300671 1,0,1,1,2,3,6,8,15,23,40,63,108,172,290,471,782,1280,2119,3474,5741, %T A300671 9432,15557,25590,42180,69413,114371,188276,310136,510637,841045, %U A300671 1384883,2280831,3755862,6185457,10185941,16774695,27624215,45492412,74916559,123374127,203172520,334587577 %N A300671 Expansion of 1/(1 - Sum_{k>=1} x^prime(k)/(1 - x^prime(k))). %C A300671 Invert transform of A001221. %H A300671 Alois P. Heinz, <a href="/A300671/b300671.txt">Table of n, a(n) for n = 0..2000</a> %H A300671 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %F A300671 G.f.: 1/(1 - Sum_{k>=2} A001221(k)*x^k). %p A300671 a:= proc(n) option remember; `if`(n=0, 1, %p A300671 add(a(n-i)*nops(ifactors(i)[2]), i=1..n)) %p A300671 end: %p A300671 seq(a(n), n=0..42); # _Alois P. Heinz_, Feb 11 2021 %t A300671 nmax = 42; CoefficientList[Series[1/(1 - Sum[x^Prime[k]/(1 - x^Prime[k]), {k, 1, nmax}]), {x, 0, nmax}], x] %t A300671 nmax = 42; CoefficientList[Series[1/(1 - Sum[PrimeNu[k] x^k, {k, 2, nmax}]), {x, 0, nmax}], x] %t A300671 a[0] = 1; a[n_] := a[n] = Sum[PrimeNu[k] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 42}] %Y A300671 Cf. A001221, A013939, A112965, A129921, A180305, A293548, A300672. %K A300671 nonn %O A300671 0,5 %A A300671 _Ilya Gutkovskiy_, Mar 11 2018