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 A064462 #11 Mar 06 2014 06:40:23
%S A064462 0,6,4,14,13,10,8,-1,9,12,-1,22,17,20,-1,16,-1,18,29,26,31,24,25,62,
%T A064462 -1,28,27,34,35,42,33,32,-1,-1,-1,36,53,40,45,-1,-1,-1,95,-1,-1,-1,79,
%U A064462 48,49,50,55,54,57,60,69,56,63,74,-1,70,67,66,65,64,77,-1
%N A064462 First row of Pascal's triangle that has n nonsquarefree entries, or -1 if no such row exists.
%C A064462 Numbers such that a(n) is -1: 7, 10, 14, 16, 24, 32, 33, 34, 39, 40, 41, 43, ... - _Michel Marcus_, Mar 05 2014
%e A064462 a(4) = 13 because C(13,5) = C(13,8) = 3^2*11*13 and C(13,6) = C(13,7) = 2^2*3*11*13.
%t A064462 f[ n_ ] := (c = 0; k = 1; While[ k < n, If[ Union[ Transpose[ FactorInteger[ Binomial[ n, k ] ] ] [ [ 2 ] ] ] [ [ -1 ] ] > 1, c++ ]; k++ ]; c); Do[ m = 2; While[ f[ m ] != n, m++ ]; Print[ m ], {n, 0, 6} ]
%o A064462 (PARI) a(n, v) = {for (i=1, #v, if (v[i] == n, return (i-1));); return (-1);} \\ where v is vector A048277; _Michel Marcus_, Mar 05 2014
%Y A064462 Cf. A048277, A064461.
%K A064462 sign
%O A064462 0,2
%A A064462 _Robert G. Wilson v_, Oct 02 2001
%E A064462 Corrected and extended by _Michel Marcus_, Mar 05 2014