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A080211 a(n) = binomial(n, smallest prime factor of n). 4
1, 1, 1, 6, 1, 15, 1, 28, 84, 45, 1, 66, 1, 91, 455, 120, 1, 153, 1, 190, 1330, 231, 1, 276, 53130, 325, 2925, 378, 1, 435, 1, 496, 5456, 561, 324632, 630, 1, 703, 9139, 780, 1, 861, 1, 946, 14190, 1035, 1, 1128, 85900584, 1225, 20825, 1326, 1, 1431, 3478761 (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..55.

FORMULA

a(n) = binomial(n, A020639(n)). - Michel Marcus, May 06 2020

MATHEMATICA

Table[Binomial[n, FactorInteger[n][[1, 1]]], {n, 60}]  (* Harvey P. Dale, Apr 12 2011 *)

PROG

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

CROSSREFS

Cf. A020639, A080212, A080213.

Sequence in context: A171006 A176121 A062190 * A146997 A147483 A050309

Adjacent sequences:  A080208 A080209 A080210 * A080212 A080213 A080214

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 06 2003

STATUS

approved

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Last modified January 25 06:44 EST 2022. Contains 350565 sequences. (Running on oeis4.)