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A278298
Expansion of ((sqrt(2);x)_inf + (-sqrt(2);x)_inf - 2)/4, where(a;q)_inf is the q-Pochhammer symbol.
1
1, 1, 2, 2, 3, 5, 6, 8, 11, 15, 18, 24, 29, 37, 48, 58, 71, 89, 108, 132, 163, 195, 236, 284, 341, 405, 486, 578, 683, 809, 954, 1120, 1319, 1543, 1806, 2112, 2457, 2857, 3320, 3850, 4451, 5149, 5936, 6840, 7879, 9047, 10376, 11900, 13613, 15561, 17770, 20266
OFFSET
1,3
COMMENTS
The q-Pochhammer symbol (a;q)_inf = Product_{k>=0} (1 - a*q^k).
a(n) agrees with A118399(n) for n < 15.
LINKS
Eric Weisstein's World of Mathematics, q-Pochhammer Symbol.
FORMULA
a(n) ~ sqrt(1 + sqrt(2)) * c^(1/4) * exp(2*sqrt(c*n)) / (8*sqrt(Pi)*n^(3/4)), where c = Pi^2/6 + log(2)^2/8 + polylog(2, -1/sqrt(2)) = 1.0944511783086747574574059... - Vaclav Kotesovec, Oct 11 2018
MATHEMATICA
((QPochhammer[Sqrt[2], x] + QPochhammer[-Sqrt[2], x] - 2)/4 + O[x]^53)[[3]]
CROSSREFS
Sequence in context: A121081 A330952 A118399 * A178927 A076571 A084783
KEYWORD
nonn
AUTHOR
STATUS
approved