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A080213 a(n) = binomial(n, greatest prime factor of n). 2
1, 1, 1, 6, 1, 20, 1, 28, 84, 252, 1, 220, 1, 3432, 3003, 120, 1, 816, 1, 15504, 116280, 705432, 1, 2024, 53130, 10400600, 2925, 1184040, 1, 142506, 1, 496, 193536720, 2333606220, 6724520, 7140, 1, 35345263800, 8122425444, 658008, 1, 26978328, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

For n>1: a(n)=1 iff n is prime.

LINKS

Table of n, a(n) for n=1..43.

FORMULA

a(n) = binomial(n, A006530(n)). - Michel Marcus, May 06 2020

MATHEMATICA

Table[Binomial[n, FactorInteger[n][[-1, 1]]], {n, 50}] (* Harvey P. Dale, Feb 25 2015 *)

PROG

(PARI) a(n) = if (n==1, 1, binomial(n, vecmax(factor(n)[, 1]))); \\ Michel Marcus, May 06 2020

CROSSREFS

Cf. A006530, A080211, A080212.

Sequence in context: A064083 A152249 A167580 * A200091 A180733 A334504

Adjacent sequences:  A080210 A080211 A080212 * A080214 A080215 A080216

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 06 2003

STATUS

approved

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Last modified May 25 04:05 EDT 2022. Contains 354048 sequences. (Running on oeis4.)