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 A251391 #8 Jul 13 2024 17:08:18 %S A251391 1,2,3,7,8,9,10,13,15,16,17,20,21,22,23,24,25,28,30,32,34,35,36,38,39, %T A251391 41,43,44,45,47,49,51,53,56,59,60,61,62,63,64,68,70,72,73,74,77,78,79, %U A251391 80,81,85,86,87,88,89,90,95,96,98,99,100,101,103,105,109 %N A251391 Indices of squarefree numbers in A098550. %C A251391 A008966(A098550(a(n))) = 1; A100112(A098550(a(n))) > 0; %C A251391 A098550(a(n)) = A005117(n). %H A251391 Reinhard Zumkeller, <a href="/A251391/b251391.txt">Table of n, a(n) for n = 1..10000</a> %o A251391 (Haskell) %o A251391 a251391 n = a251391_list !! (n-1) %o A251391 a251391_list = filter ((== 1) . a008966 . fromIntegral . a098550) [1..] %Y A251391 Cf. A098550, A005117, A008966, A100112, A251239 (subsequence). %K A251391 nonn %O A251391 1,2 %A A251391 _Reinhard Zumkeller_, Dec 02 2014