A183222 Complement of the 10-gonal numbers.

2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 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, 79, 80, 81, 82, 83, 84, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102

Offset

1,1

Links

Table of n, a(n) for n=1..97.

Formula

a(n) = n - 1 + ceiling(1/2 + ((n+1)/4)^(1/2)).

a(n) = n + floor((n^(1/2)+1)/2). - Chai Wah Wu, Oct 05 2024

Mathematica

Table[n-1+Ceiling[1/2+((n+1)/4)^(1/2)], {n, 100}]

Prog

(Python)
from math import isqrt
def A183222(n): return n+(isqrt(n)+1>>1) # Chai Wah Wu, Oct 05 2024

Crossrefs

Cf. A001107 (10-gonal numbers).

Sequence in context: A118764 A226134 A057717 * A063742 A014089 A065039

Adjacent sequences: A183219 A183220 A183221 * A183223 A183224 A183225

Keyword

nonn

Author

Clark Kimberling, Jan 01 2011

Status

approved