A231895 - OEIS

A231895

a(n) = 2*A000111(n+1) + A000111(n).

3, 3, 5, 12, 37, 138, 605, 3042, 17257, 108978, 758105, 5759322, 47439277, 421090218, 4006875605, 40686781602, 439122198097, 5019624693858, 60582649901105, 769831261587882, 10273367294485717, 143649246839399898, 2100196647406842605, 32044492213621026162, 509357494543973054137

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

It is clear from the Berry et al. article that they intended to consider 2*A000111(n+1) - A000111(n) (which is A104854), not 2*A000111(n+1) + A000111(n).

LINKS

Table of n, a(n) for n=0..24.

D. Berry, J. Broom, D. Dixon, and A. Flaherty, Umbral Calculus and the Boustrophedon Transform, 2013.

FORMULA

E.g.f.: 1 + (sec(x) + tan(x) + 1)*(sec(x) + tan(x)). - Sergei N. Gladkovskii, Jun 11 2015

PROG

(Python)

from itertools import accumulate, islice

def A231895_gen(): # generator of terms

yield 3

blist = (0, 1)

while True: