A291100 Number of maximal irredundant sets in the n-ladder graph.

2, 6, 9, 18, 54, 99, 216, 512, 1079, 2352, 5225, 11383, 24991, 54814, 120126, 263554, 577644, 1266485, 2777763, 6089610, 13352283, 29278137, 64194490, 140755609, 308628427, 676706615, 1483775356, 3253378624, 7133479611, 15641147936, 34295353874, 75197276962

Offset

1,1

Links

Christian Sievers, Table of n, a(n) for n = 1..200

Eric Weisstein's World of Mathematics, Ladder Graph.

Eric Weisstein's World of Mathematics, Maximal Irredundant Set.

Index entries for linear recurrences with constant coefficients, signature (1,1,3,1,0,5,-7,-2,-15,17,19,-8,-15,-27,21,-22,-48,-6,38,34,-43,2,56,8,-42,-22,24,24,-20,-8,0,8).

Formula

a(n) = a(n-1)+a(n-2)+3*a(n-3)+a(n-4)+5*a(n-6)-7*a(n-7)-2*a(n-8)-15*a(n-9)+17*a(n-10)+19*a(n-11)-8*a(n-12)-15*a(n-13)-27*a(n-14)+21*a(n-15)-22*a(n-16)-48*a(n-17)-6*a(n-18)+38*a(n-19)+34*a(n-20)-43*a(n-21)+2*a(n-22)+56*a(n-23)+8*a(n-24)-42*a(n-25)-22*a(n-26)+24*a(n-27)+24*a(n-28)-20*a(n-29)-8*a(n-30)+8*a(n-32). - Eric W. Weisstein, Sep 30 2025

Mathematica

LinearRecurrence[{1, 1, 3, 1, 0, 5, -7, -2, -15, 17, 19, -8, -15, -27, 21, -22, -48, -6, 38, 34, -43, 2, 56, 8, -42, -22, 24, 24, -20, -8, 0, 8}, {2, 6, 9, 18, 54, 99, 216, 512, 1079, 2352, 5225, 11383, 24991, 54814, 120126, 263554, 577644, 1266485, 2777763, 6089610, 13352283, 29278137, 64194490, 140755609, 308628427, 676706615, 1483775356, 3253378624, 7133479611, 15641147936, 34295353874, 75197276962}, 20] (* Eric W. Weisstein, Sep 30 2025 *)

Crossrefs

Sequence in context: A285446 A367464 A076738 * A361271 A082290 A325536

Adjacent sequences: A291097 A291098 A291099 * A291101 A291102 A291103

Keyword

nonn,easy,changed

Author

Eric W. Weisstein, Aug 17 2017

Extensions

a(13) = 24991 from Eric W. Weisstein, Feb 16 2018

a(14) = 54814 from Eric W. Weisstein, Mar 20 2022

More terms from Christian Sievers, Nov 16 2023

Status

approved