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 A280195 #16 Feb 16 2025 08:33:38 %S A280195 1,0,1,1,2,3,4,8,11,19,28,47,72,116,182,289,460,724,1153,1820,2891, %T A280195 4572,7249,11482,18190,28821,45651,72338,114582,181549,287596,455647, %U A280195 721847,1143588,1811748,2870239,4547232,7203907,11412882,18080833,28644680,45380392,71894054,113898439,180443915,285869028,452888824,717490903,1136687237 %N A280195 Expansion of 1/(1 - Sum_{k>=2} floor(1/omega(k))*x^k), where omega(k) is the number of distinct prime factors (A001221). %C A280195 Number of compositions (ordered partitions) into prime powers (1 excluded). %H A280195 G. C. Greubel, <a href="/A280195/b280195.txt">Table of n, a(n) for n = 0..1000</a> %H A280195 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimePower.html">Prime Power</a> %H A280195 <a href="/index/Com#comp">Index entries for sequences related to compositions</a> %F A280195 G.f.: 1/(1 - Sum_{k>=2} floor(1/omega(k))*x^k). %e A280195 a(6) = 4 because we have [4, 2], [3, 3], [2, 4] and [2, 2, 2]. %t A280195 nmax = 48; CoefficientList[Series[1/(1 - Sum[Floor[1/PrimeNu[k]] x^k, {k, 2, nmax}]), {x, 0, nmax}], x] %Y A280195 Cf. A001221, A023360, A023894, A246655. %K A280195 nonn %O A280195 0,5 %A A280195 _Ilya Gutkovskiy_, Dec 28 2016