OFFSET
1,4
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1275 (rows 1..50)
FORMULA
G.f.: -1 + exp(Sum_{k>=1} y^k*B(x^k)/k) where B(x) = x*(1 - 2*x + 2*x^2)/((1 - x)*(1 - 2*x)). - Andrew Howroyd, Jan 13 2022
EXAMPLE
Triangle begins:
1;
1, 1;
3, 1, 1;
7, 4, 1, 1;
15, 10, 4, 1, 1;
31, 28, 11, 4, 1, 1;
63, 67, 31, 11, 4, 1, 1;
127, 167, 80, 32, 11, 4, 1, 1;
...
PROG
(PARI)
B(x) = x*(1 - 2*x + 2*x^2)/((1 - x)*(1 - 2*x))
T(n)=[Vecrev(p/y) | p<-Vec(-1 + exp(sum(k=1, n, y^k*B(x^k)/k + O(x*x^n))))]
{ my(A=T(8)); for(n=1, #A, print(A[n])) } \\ Andrew Howroyd, Jan 13 2022
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Salah Uddin Mohammad, Jan 09 2022
STATUS
approved