A004271 1, 3 and the nonnegative even numbers.

0, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104

Offset

0,3

Links

Table of n, a(n) for n=0..54.

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Formula

a(n) = 2*n - 4 + floor(3/n) + delta_{n,2}, n > 0. - Wesley Ivan Hurt, May 23 2013

a(n) = max(2n-4, n) = n + max(n-4,0). - M. F. Hasler, Oct 30 2019

From Chai Wah Wu, Feb 03 2021: (Start)

a(n) = 2*a(n-1) - a(n-2) for n > 5.

G.f.: (x^5 + x)/(x - 1)^2. (End)

Prog

(PARI) a(n)=n+if(n>4, n-4) \\ M. F. Hasler, Oct 30 2019

Crossrefs

Sequence in context: A137291 A032954 A158023 * A004278 A333183 A068670

Adjacent sequences: A004268 A004269 A004270 * A004272 A004273 A004274

Keyword

easy,nonn

Author

N. J. A. Sloane

Status

approved