A183669 Number of (n+1) X 7 0..6 arrays with every 2 X 2 subblock summing to 12.

1577065, 3791935, 10914505, 35840623, 129866905, 508151455, 2115695785, 9273350863, 42447215545, 201645637375, 989278296265, 4992450573103, 25832066228185, 136670703353695, 737680689907945, 4054076079123343, 22647536502520825, 128419998043668415, 738229902365122825

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..1000

Christian Krause, Proof of formula, Jun 13 2026.

Index entries for linear recurrences with constant coefficients, signature (28,-322,1960,-6769,13132,-13068,5040).

Formula

a(n) = 7*7^n + 756*6^n + 9660*5^n + 48552*4^n + 142632*3^n + 280140*2^n + 341796. - Christian Krause, Jun 13 2026

Example

Some solutions for 3 X 7:
..0..4..1..5..3..2..3....0..3..1..0..6..5..3....0..3..5..4..3..4..4
..6..2..5..1..3..4..3....6..3..5..6..0..1..3....6..3..1..2..3..2..2
..1..3..2..4..4..1..4....0..3..1..0..6..5..3....0..3..5..4..3..4..4

Mathematica

A183669[n_] := 7*7^n + 756*6^n + 9660*5^n + 48552*4^n + 142632*3^n + 280140*2^n + 341796;
Array[A183669, 25] (* Paolo Xausa, Jun 16 2026 *)

Crossrefs

Column 6 of A183672.

Sequence in context: A186920 A185804 A252881 * A234830 A262185 A104827

Adjacent sequences: A183666 A183667 A183668 * A183670 A183671 A183672

Keyword

nonn,easy

Author

R. H. Hardin, Jan 06 2011

Extensions

a(6)-a(19) from Christian Krause, Jun 13 2026

Status

approved