

A064462


First row of Pascal's triangle that has n nonsquarefree entries, or 1 if no such row exists.


2



0, 6, 4, 14, 13, 10, 8, 1, 9, 12, 1, 22, 17, 20, 1, 16, 1, 18, 29, 26, 31, 24, 25, 62, 1, 28, 27, 34, 35, 42, 33, 32, 1, 1, 1, 36, 53, 40, 45, 1, 1, 1, 95, 1, 1, 1, 79, 48, 49, 50, 55, 54, 57, 60, 69, 56, 63, 74, 1, 70, 67, 66, 65, 64, 77, 1
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OFFSET

0,2


COMMENTS

Numbers such that a(n) is 1: 7, 10, 14, 16, 24, 32, 33, 34, 39, 40, 41, 43, ...  Michel Marcus, Mar 05 2014


LINKS



EXAMPLE

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.


MATHEMATICA

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} ]


PROG

(PARI) a(n, v) = {for (i=1, #v, if (v[i] == n, return (i1)); ); return (1); } \\ where v is vector A048277; Michel Marcus, Mar 05 2014


CROSSREFS



KEYWORD

sign


AUTHOR



EXTENSIONS



STATUS

approved



