A020705 a(n) = n + 4.

4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78

Offset: 0

Author

David W. Wilson

Keywords

• nonn
• easy

Comments

Pisot sequences E(4,5), P(4,5), T(4,5).

Links

• Tanya Khovanova, Recursive Sequences.
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

See A008776 for definitions of Pisot sequences.

Cf. A020744, A055999.

Programs

Mathematica

Range[4, 100] (* Wesley Ivan Hurt, May 17 2023 *)

PARI

a(n)=n+4

Formula

a(n) = 2*a(n-1) - a(n-2).

From Elmo R. Oliveira, Oct 30 2024: (Start)

G.f.: (4 - 3*x)/(1 - x)^2.

E.g.f.: (4 + x)*exp(x).

a(n) = A020744(n)/2 = A055999(n+1) - A055999(n). (End)