

A286980


Binomial coefficients binomial(n,k) = uv such that n>=2k and u > v, where gpf(u) < k, gpf(v) >= k (gpf(n)= is the greatest prime factor of n).


1



56, 126, 252, 792, 116280, 203490, 2035800, 573166440, 818809200, 2310789600, 8597496600, 1889912732400
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OFFSET

1,1


COMMENTS

The corresponding pairs (n,k) are: (8,3), (9,4), (10,5), (12,5), (21,7), (21,8), (30,7), (33,13), (33,14), (36,13), (36,17), (56,13).


LINKS



EXAMPLE

56 = Binomial(8,3) = 8*7, gpf(8) = 2 < 3 and gpf(7) = 7 >= 3, and 8 > 7, thus 56 is in the sequence.


CROSSREFS



KEYWORD

nonn,fini,full


AUTHOR



STATUS

approved



