OFFSET
1,3
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..505
FORMULA
a(n) = floor((n+1)!/2^n). - Yifan Xie, Mar 05 2023
EXAMPLE
a(4) = 7, because, the first four triangular numbers being 1, 3, 6, 10, their product is 180, which divided by 4! is 15/2 = 7.5.
a(5) = 22, because, the first five triangular numbers being 1, 3, 6, 10, 15, their product is 2700, which divided by 5! is 45/2 = 22.5.
MATHEMATICA
With[{nn=30}, Floor[#[[1]]/#[[2]]]&/@Thread[{FoldList[Times, Accumulate[ Range[ nn]]], Range[nn]!}]] (* Harvey P. Dale, Apr 02 2017 *)
PROG
(Python)
f=t=1
for n in range(1, 33):
t*=n*(n+1)/2
f*=n
print str(t/f)+', ',
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Dec 03 2013
STATUS
approved