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 A326864 G.f.: Product_{k>=1} (1 + x^k/k^2) = Sum_{n>=0} a(n)*x^n/n!^2. 4
 1, 1, 1, 13, 100, 1876, 57636, 2051316, 104640768, 6819033600, 576652089600, 57187381536000, 7057192160793600, 1014733052692300800, 172646881540527744000, 33848454886497227289600, 7637231669166956976537600, 1948418678155880277481881600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS EXAMPLE a(n) ~ c * (n-1)!^2, where c = A156648 = Product_{k>=1} (1 + 1/k^2) = sinh(Pi)/Pi = 3.67607791037497772... MATHEMATICA nmax = 20; CoefficientList[Series[Product[(1+x^k/k^2), {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!^2 CROSSREFS Cf. A007838, A249588, A326865. Sequence in context: A089936 A196928 A266002 * A083341 A336347 A075604 Adjacent sequences:  A326861 A326862 A326863 * A326865 A326866 A326867 KEYWORD nonn AUTHOR Vaclav Kotesovec, Jul 27 2019 STATUS approved

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Last modified December 2 08:31 EST 2021. Contains 349437 sequences. (Running on oeis4.)