A374165 Expansion of g.f. (1 - x)*(1 - 2*x)(1 - 4*x)/(1 - 8*x + 20*x^2 - 18*x^3 + 3*x^4).

1, 1, 2, 6, 23, 97, 418, 1800, 7717, 32969, 140558, 598590, 2547851, 10842145, 46133086, 196287336, 835152025, 3553338593, 15118441034, 64324630854, 273682864751, 1164442223761, 4954368527338, 21079421416440, 89686912218205, 381592176237641, 1623565645450934, 6907807794533022

Offset: 0

Author

Stefano Spezia, Jun 30 2024

Keywords

• nonn
• easy

Links

• Lapo Cioni, Luca Ferrari, and Rebecca Smith, Pop Stacks with a Bypass, arXiv:2406.16399 [cs.DM], 2024. See p. 78.
• Index entries for linear recurrences with constant coefficients, signature (8,-20,18,-3).

Crossrefs

Cf. A374162.

Programs

Mathematica

CoefficientList[Series[(1-x)(1-2x)(1-4x)/(1-8x+20x^2-18x^3+3x^4),{x,0,27}],x]

Formula

a(n) = 8*a(n-1) - 20*(n-2) + 18*a(n-3) - 3*a(n-4) for n > 3.