A028493 a(0) = 16, a(n+1) = 3a(n) - (6-n)^2.

16, 12, 11, 17, 42, 122, 365, 1095, 3284, 9848, 29535, 88589, 265742, 797190, 2391521, 7174499, 21523416, 64570148, 193710323, 581130825, 1743392306, 5230176722, 15690529941, 47071589567, 141214768412

Offset

0,1

References

Seen in a newspaper quiz.

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Formula

From Chai Wah Wu, Mar 29 2017: (Start)

a(n) = 6*a(n-1) - 12*a(n-2) + 10*a(n-3) - 3*a(n-4) for n > 3.

G.f.: (-65*x^3 + 131*x^2 - 84*x + 16)/((x - 1)^3*(3*x - 1)). (End)

Maple

(3^n + (5-n)*(6-n) + 1)/2;

Mathematica

nxt[{n_, a_}]:={n+1, 3a-(6-n)^2}; NestList[nxt, {0, 16}, 30][[;; , 2]] (* Harvey P. Dale, Sep 07 2024 *)

Crossrefs

Sequence in context: A008665 A076823 A070551 * A291426 A299524 A070534

Adjacent sequences: A028490 A028491 A028492 * A028494 A028495 A028496

Keyword

nonn,easy

Author

Mark Orr (mjo(AT)cns.ed.ac.uk)

Extensions

Definition edited by Chai Wah Wu, Mar 29 2017

Status

approved