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A145062 Generalized Bessel numbers. 1
1, 1, 2, 3, 6, 12, 28, 69, 182, 497, 1399, 4028, 11852, 35626, 109494, 344338, 1108565, 3653536, 12320940, 42483305, 149640000, 537975261, 1972713660, 7374794356, 28100132482, 109117922021, 431821675389, 1741507272791 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Hankel transform of a(n) is 1,1,1,... (by construction). Hankel transform of a(n+1) is A145063.

Is this the same as the sequence s(n) that can be seen in Fig. 8 of Zhang (2015), with a different offset? - N. J. A. Sloane, Jan 28 2016

LINKS

Table of n, a(n) for n=0..27.

Yan X Zhang, Four Variations on Graded Posets, arXiv preprint arXiv:1508.00318 [math.CO], 2015.

FORMULA

G.f.: 1/(1-x-x^2/(1-0x-x^2/(1-2x-x^2/(1-0x-x^2/(1-3x-x^2/...))))) (a continued fraction).

G.f.: 1/(U(0)+x^2) where U(k)= 1 - x*(k+1) - 2*x^2 - x^4/U(k+1) ; (continued fraction, 3rd kind, 3-step). - Sergei N. Gladkovskii, Oct 23 2012

CROSSREFS

Cf. A006789.

Sequence in context: A073431 A273873 A003317 * A300323 A261230 A014278

Adjacent sequences:  A145059 A145060 A145061 * A145063 A145064 A145065

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Sep 30 2008

STATUS

approved

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Last modified November 21 09:14 EST 2019. Contains 329362 sequences. (Running on oeis4.)