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 A118663 #18 May 13 2023 13:41:16 %S A118663 1,1,1,2,1,1,1,2,1,1,1,2,1,1,3,1,2,1,1,1,2,1,3,1,1,2,1,1,1,2,1,1,4,1, %T A118663 2,1,1,3,1,2,1,1,1,2,1,3,1,1,2,1,1,1,2,1,4,1,1,2,1,1,3,1,2,1,1,4,1,2, %U A118663 1,3,1,1,2,1,1,1,2,1,1,1,2,1,1,3,1,2,1,4,1,5,1,2,1,3,1,1,2,1,1,4,1,2,1,1,1,2 %N A118663 Index of the least prime dividing the n-th composite number: A000720(A020639(A002808(n))). %H A118663 Harvey P. Dale, <a href="/A118663/b118663.txt">Table of n, a(n) for n = 1..1000</a> %F A118663 A118663 = A000720 o A056608. - _M. F. Hasler_, Apr 03 2012 %t A118663 PrimePi[FactorInteger[#][[1,1]]]&/@Select[Range[200],CompositeQ] (* _Harvey P. Dale_, May 13 2023 *) %o A118663 (PARI) for(i=2,999,isprime(i)||print1(primepi(factor(i)[1,1])",")) \\ - _M. F. Hasler_, Apr 03 2012 %Y A118663 Cf. A056608. %K A118663 easy,nonn %O A118663 1,4 %A A118663 _Giovanni Teofilatto_, May 19 2006