A184004 a(n) = n + floor(sqrt(4n/3)); complement of A184005.

2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 90

Offset: 1

Author

Clark Kimberling, Jan 08 2011

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A184005.

Programs

Mathematica

a=4/3; b=0;
Table[n+Floor[(a*n+b)^(1/2)],{n,80}]
Table[n-1+Ceiling[(n*n-b)/a],{n,60}]

PARI

for(n=1, 100, print1(n + floor(sqrt(4*n/3)), ", ")) \\ G. C. Greubel, Jul 22 2017

PARI

a(n) = n + sqrtint(4*n/3); \\ Michel Marcus, Oct 01 2024

Python

from math import isqrt
def A184004(n): return n+isqrt((n<<2)//3) # Chai Wah Wu, Oct 01 2024