A284995 a(n) = ceiling(Gamma(n/2)).
2, 1, 1, 1, 2, 2, 4, 6, 12, 24, 53, 120, 288, 720, 1872, 5040, 14035, 40320, 119293, 362880, 1133279, 3628800, 11899424, 39916800, 136843366, 479001600, 1710542069, 6227020800, 23092317923, 87178291200, 334838609874, 1307674368000, 5189998453041
Offset: 1
Examples
Let s = sqrt(Pi); for n>=1, gamma(n/2) takes the values s, 1, s/2, 1, 3s/4, 2, 15s/8, 6, so that a(n) begins with 1,1,0,1,1,2,3,6.
Links
- Clark Kimberling, Table of n, a(n) for n = 1..500
Programs
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Mathematica
Table[Ceiling[Gamma[n/2]], {n, 1, 35}]
Comments