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A037031 Number of combinations of n objects taken pi(n) at a time. 1
1, 2, 3, 6, 10, 20, 35, 70, 126, 210, 462, 792, 1716, 3003, 5005, 8008, 19448, 31824, 75582, 125970, 203490, 319770, 817190, 1307504, 2042975, 3124550, 4686825, 6906900, 20030010, 30045015, 84672315, 129024480, 193536720, 286097760 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = C(n, pi(n)).

EXAMPLE

C(16, 6) = 8008.

MAPLE

with(numtheory); A037031:=n->binomial(n, pi(n)); seq(A037031(k), k=1..100); # Wesley Ivan Hurt, Oct 19 2013

MATHEMATICA

Table[Binomial[n, PrimePi[n]], {n, 40}] (* Harvey P. Dale, Mar 22 2012 *)

CROSSREFS

Cf. A000720.

Sequence in context: A061551 A026034 A178381 * A056202 A001405 A126930

Adjacent sequences:  A037028 A037029 A037030 * A037032 A037033 A037034

KEYWORD

nonn

AUTHOR

G. L. Honaker, Jr.

STATUS

approved

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Last modified October 18 05:17 EDT 2018. Contains 316304 sequences. (Running on oeis4.)