316234143225
domain: N
Appears in sequences
- Double factorial of odd numbers: a(n) = (2*n-1)!! = 1*3*5*...*(2*n-1).at n=12A001147
- Double factorials n!!: a(n) = n*a(n-2) for n > 1, a(0) = a(1) = 1.at n=23A006882
- 2-adic factorial function.at n=24A055634
- Volume of n-dimensional sphere of radius r is V_n*r^n = Pi^(n/2)*r^n/(n/2)! = C_n*Pi^floor(n/2)*r^n; sequence gives denominator of C_n.at n=23A072346
- Surface area of n-dimensional sphere of radius r is n*V_n*r^(n-1) = n*Pi^(n/2)*r^(n-1)/(n/2)! = S_n*Pi^floor(n/2)*r^(n-1); sequence gives denominator of S_n.at n=25A072479
- a(n) = (n+1)*a(n-2) with a(0) = a(1) = 1.at n=22A081405
- Double factorial of primes.at n=8A091835
- Row 4 of array in A288580.at n=23A092398
- a(n) = (4n)! / ( 4^n * (2n)! ).at n=6A101485
- a(n) = (n-1)*a(n-2), a(0)=1, a(1)=0.at n=24A123023
- Q(1,n), where Q(m,k) is defined in A127080 and A127137.at n=24A127138
- A001147 with each term repeated.at n=24A133221
- A001147 with each term repeated.at n=25A133221
- List of pairs of numbers: {n^2-1, (2*n-1)!!} such that F((2*n-1)!!) = n^2 - 1.at n=23A154029
- a(n) = n!! mod !n.at n=21A216443
- a(n) = n!! mod n!at n=23A216466
- Union of the factorial numbers (A000142) and the double factorials of odd numbers (A001147).at n=24A248652
- If n is even then a(n) = n!/( 2^(n/2)*(n/2)! ), otherwise a(n) = n!/( 3*2^((n-1)/2)*((n-3)/2)! ).at n=22A259877
- Union of the factorial numbers (A000142) and the double factorials numbers (A006882).at n=34A268645
- Number of (n+floor(n/2))-block bicoverings of an n-set.at n=24A275521