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Search: id:A064462
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| A064462 |
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First row of Pascal's triangle that has n non-squarefree entries, or -1 if no such row exists. |
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+0
3
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OFFSET
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0,1
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EXAMPLE
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a(13) = 4 because C(13,5) = C(13,8) = 3^2*11*13 and C(13,6) = C(13,7) = 2^2*3*11*13.
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MATHEMATICA
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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} ]
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CROSSREFS
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Cf. A064460, A064461.
Sequence in context: A046204 A163755 A100851 this_sequence A111807 A069914 A130190
Adjacent sequences: A064459 A064460 A064461 this_sequence A064463 A064464 A064465
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KEYWORD
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easy,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 02 2001
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