A125813 q-Bell numbers for q=3; eigensequence of A022167, which is the triangle of Gaussian binomial coefficients [n,k] for q=3.
1, 1, 2, 7, 47, 628, 17327, 1022983, 132615812, 38522717107, 25526768401271, 39190247441314450, 141213238745969102393, 1207367655155905204747681, 24733467452839301566047854678, 1224709126636123500201799360630423, 147747406166666863538672620806542995763
Offset: 0
Keywords
Examples
The recurrence: a(n) = Sum_{k=0..n-1} A022167(n-1,k) * a(k) is illustrated by: a(2) = 1*(1) + 4*(1) + 1*(2) = 7; a(3) = 1*(1) + 13*(1) + 13*(2) + 1*(7) = 47; a(4) = 1*(1) + 40*(1) + 130*(2) + 40*(7) + 1*(47) = 628. Triangle A022167 begins: 1; 1, 1; 1, 4, 1; 1, 13, 13, 1; 1, 40, 130, 40, 1; 1, 121, 1210, 1210, 121, 1; 1, 364, 11011, 33880, 11011, 364, 1; ...
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..72
Programs
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Maple
b:= proc(o, u, t) option remember; `if`(u+o=0, 1, `if`(t>0, b(u+o, 0$2), 0)+add(3^(u+j-1)* b(o-j, u+j-1, min(2, t+1)), j=`if`(t=0, 1, 1..o))) end: a:= n-> b(n, 0$2): seq(a(n), n=0..18); # Alois P. Heinz, Feb 21 2025
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Mathematica
b[o_, u_, t_] := b[o, u, t] = If[u + o == 0, 1, If[t > 0, b[u + o, 0, 0], 0] + Sum[3^(u + j - 1)* b[o - j, u + j - 1, Min[2, t + 1]], {j, If[t == 0, {1}, Range[o]]}]]; a[n_] := b[n, 0, 0]; Table[a[n], {n, 0, 18}] (* Jean-François Alcover, Mar 15 2025, after Alois P. Heinz *)
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PARI
/* q-Binomial coefficients: */ C_q(n,k)=if(n
Formula
a(n) = Sum_{k=0..n-1} A022167(n-1,k) * a(k) for n>0, with a(0)=1.
a(n) = Sum_{k>=0} 3^k * A125810(n,k). - Alois P. Heinz, Feb 21 2025
Comments