A183862 a(n) = n + floor(sqrt(5*n/2)); complement of A183863.

2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 93, 94

Offset

1,1

Comments

Also n + floor(sqrt(5*n/2 + 1/2)) since 5*n/2 + 1/2 is never a square. - Charles R Greathouse IV, Feb 11 2011

Links

Table of n, a(n) for n=1..80.

Mathematica

a=5/2; b=1/2;
Table[n+Floor[(a*n+b)^(1/2)], {n, 80}]
Table[n-1+Ceiling[(n*n-b)/a], {n, 70}]

Prog

(PARI) a(n)=n+sqrtint(5*n/2)

Crossrefs

Cf. A183863.

Sequence in context: A253723 A014132 A184008 * A254058 A346128 A276220

Adjacent sequences: A183859 A183860 A183861 * A183863 A183864 A183865

Keyword

nonn,easy

Author

Clark Kimberling, Jan 07 2011

Status

approved