A370966 a(n) = number of max-closed 2 X 2 X n relations.

1, 14, 122, 898, 6086, 39394, 248102, 1536178, 9409046, 57227074, 346467782, 2091269458, 12597590006, 75785795554, 455516874662, 2736312874738, 16430733386966, 98635853704834, 592021022116742, 3552949991056018, 21320996155647926, 127939164097754914, 767687740219762022

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Don Knuth, Parades and poly-Bernoulli bijections, Mar 31 2024. See (19.14) and (19.16).

Filip Stappers, Problems concerning parades and poly-Bernoulli numbers, 2024. See Problem 10.

Index entries for linear recurrences with constant coefficients, signature (15,-80,180,-144).

Formula

From Filip Stappers, Aug 19 2024: (Start)

a(n) = 35/6*6^n - 6*4^n + 2/3*3^n + 1/2*2^n.

G.f.: (1-z)*(1-8*z^2) / ((1-6*z)*(1-4*z)*(1-3*z)*(1-2*z)). (End)

E.g.f.: exp(2*x)*(3 + 4*exp(x) - 36*exp(2*x) + 35*exp(4*x)). - Stefano Spezia, Aug 20 2024

Crossrefs

Cf. A370967, A371761.

Sequence in context: A206635 A163942 A206628 * A235710 A239544 A167567

Adjacent sequences: A370963 A370964 A370965 * A370967 A370968 A370969

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 04 2024

Extensions

a(7)-a(9) from Michael S. Branicky, Apr 07 2024

a(10) from Michael S. Branicky, Apr 08 2024

a(11) from Michael S. Branicky, Apr 22 2024

More terms from Filip Stappers, Aug 14 2024

a(0)=1 prepended by Filip Stappers, Aug 19 2024

Status

approved