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
Offset: 0
Keywords
Links
- D. Berry, J. Broom, D. Dixon, and A. Flaherty, Umbral Calculus and the Boustrophedon Transform, 2013.
Programs
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Python
from itertools import accumulate, islice def A231895_gen(): # generator of terms yield 3 blist = (0,1) while True: yield blist[-1]+2*(blist := tuple(accumulate(reversed(blist),initial=0)))[-1] A231895_list = list(islice(A231895_gen(),40)) # Chai Wah Wu, Jun 14 2022
Formula
E.g.f.: 1 + (sec(x) + tan(x) + 1)*(sec(x) + tan(x)). - Sergei N. Gladkovskii, Jun 11 2015
Comments