OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..500
FORMULA
a(n) = 60*(13*n+9)*(4*n+5)!/((3*n+9)!*(n-1)!).
PROG
(PARI) a(n)={60*(13*n+9)*(4*n+5)!/((3*n+9)!*(n-1)!)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Feb 23 2021
STATUS
approved