OFFSET
0,2
COMMENTS
a(n) is the number of all 64-subgroups of R^n, where R^n is a near-vector space over a proper nearfield R.
LINKS
Prudence Djagba and Jan Hązła, Combinatorics of subgroups of Beidleman near-vector spaces, arXiv:2306.16421 [math.RA], 2023. See pp. 7-8.
Paweł Hitczenko, A class of polynomial recurrences resulting in (n/log n, n/log^2 n)-asymptotic normality, arXiv:2403.03422 [math.CO], 2024. See p. 8.
FORMULA
E.g.f.: exp(x + (exp(63*x) - 1)/63).
a(n) = exp(-1/63) * Sum_{k>=0} (63*k + 1)^n / (63^k * k!).
a(n) ~ 63^(n + 1/63) * n^(n + 1/63) * exp(n/LambertW(63*n) - n - 1/63) / (sqrt(1 + LambertW(63*n)) * LambertW(63*n)^(n + 1/63)).
a(n) = Sum_{k=0..n} Sum_{d=0..n-k} binomial(n, d)*StirlingS2(n-d, k)*63^(n-d-k).
MATHEMATICA
With[{m=16, b=63}, CoefficientList[Series[Exp[x +(Exp[b*x]-1)/b], {x, 0, m}], x]*Range[0, m]!] (* or *)
a[n_]:=Sum[Sum[Binomial[n, d]StirlingS2[n-d, k]63^(n-d-k), {d, 0, n-k}], {k, 0, n}]; Array[a, 17, 0]
CROSSREFS
KEYWORD
nonn
AUTHOR
Stefano Spezia, Jul 04 2023
STATUS
approved