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A110374 a(n) = Sum_{composite c <= n} n!/c. 7
6, 30, 300, 2100, 21840, 236880, 2731680, 30048480, 400498560, 5206481280, 79117758720, 1273944672000, 21690789120000, 368743415040000, 6993068898816000, 132868309077504000, 2779011281958912000, 60792138929313792000, 1388517998616612864000 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Michael S. Branicky, Table of n, a(n) for n = 4..449

EXAMPLE

a(8) = 8! * (1/4 + 1/6 + 1/8) = 21840.

MAPLE

a:=proc(n) local s, i :s:=0: for i from 4 to n do if isprime(i)=false then s:=s+1/i else s:=s: fi od: n!*s; end; seq(a(n), n=4..23); # Emeric Deutsch, Jul 24 2005

PROG

(Python)

from sympy import factorial, isprime, Rational

def a(n): return factorial(n) * sum(Rational(1, c) for c in range(4, n+1) if not isprime(c))

print([a(n) for n in range(4, 23)]) # Michael S. Branicky, Jun 30 2021

CROSSREFS

Cf. A110373.

Sequence in context: A215288 A295611 A264641 * A232978 A332041 A201135

Adjacent sequences:  A110371 A110372 A110373 * A110375 A110376 A110377

KEYWORD

easy,nonn

AUTHOR

Amarnath Murthy, Jul 24 2005

EXTENSIONS

More terms from Emeric Deutsch, Jul 24 2005

a(21) and beyond from Michael S. Branicky, Jun 30 2021

STATUS

approved

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Last modified December 5 10:11 EST 2021. Contains 349543 sequences. (Running on oeis4.)