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A138524
a(n) = Sum_{k=1..n} (2*k)!.
5
2, 26, 746, 41066, 3669866, 482671466, 87660962666, 21010450850666, 6423384156578666, 2439325392333218666, 1126440053169940898666, 621574841786409380258666, 403913035968392044964258666, 305292257647682252546468258666
OFFSET
1,1
LINKS
FORMULA
A007623(a(n)) = A163662(n). - Amiram Eldar, Apr 07 2022
MATHEMATICA
Table[Sum[(2*i)!, {i, n}], {n, 15}] (* Stefan Steinerberger, Mar 25 2008 *)
Accumulate[(2*Range[20])!] (* Harvey P. Dale, Nov 12 2016 *)
PROG
(PARI) for(n=1, 25, print1(sum(k=1, n, (2*k)!), ", ")) \\ G. C. Greubel, Sep 29 2017
(Python)
from math import factorial
def a(n): return sum(factorial(2*k) for k in range(1, n+1))
print([a(n) for n in range(1, 16)]) # Michael S. Branicky, Feb 26 2021
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Mar 23 2008
EXTENSIONS
More terms from Stefan Steinerberger and Robert G. Wilson v, Mar 25 2008
STATUS
approved