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 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 (list; graph; refs; listen; history; text; internal format)
 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). Subsequence of A286981. LINKS Table of n, a(n) for n=1..12. Earl F. Ecklund, Jr., Roger B. Eggleton, Paul Erdős and John L. Selfridge, On the prime factorization of binomial coefficients, Journal of the Australian Mathematical Society (Series A), Vol. 26, No. 3 (1978), pp. 257-269. 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 Cf. A007318, A286981. Sequence in context: A157330 A038849 A003781 * A254463 A030443 A135803 Adjacent sequences: A286977 A286978 A286979 * A286981 A286982 A286983 KEYWORD nonn,fini,full AUTHOR Amiram Eldar, May 17 2017 STATUS approved

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Last modified September 9 17:35 EDT 2024. Contains 375765 sequences. (Running on oeis4.)