OFFSET
0,2
FORMULA
D-finite with recurrence a(n) = a(n-1)*((14*n + 2)*(2*n - 3))/((7*n - 6)*(n + 1)) for n >= 2.
MAPLE
alias(PS = ListTools:-PartialSums):
aList := proc(len) local a, k, P, T; a := 4; P := [1]; T := [1];
for k from 0 to len-1 do T := [op(T), a]; P := PS([op(P), a]); a := P[-1] od;
T end: aList(27);
# Alternative:
a := proc(n) option remember; if n = 0 then 1 elif n = 1 then 4 else
a(n-1)*((14*n + 2)*(2*n - 3))/((7*n - 6)*(n + 1)) fi end: seq(a(n), n = 0..27);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Luschny, Mar 27 2022
STATUS
approved