A183223 Complement of the 11-gonal numbers.

2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 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, 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, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 96, 97, 98, 99, 100, 101, 102

Offset

1,1

Links

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

Formula

a(n) = n + floor(1/2+(2n/9+2/9)^(1/2)).

Mathematica

 Table[n+Floor[1/2+(2n/9+2/9)^(1/2)], {n, 100}]

Prog

(Python)
from math import isqrt
def A183223(n): return n+(isqrt((n<<3|4)//9)+1>>1) # Chai Wah Wu, Oct 06 2024

Crossrefs

Cf. A051682 (11-gonal numbers).

Sequence in context: A331162 A337843 A101947 * A167520 A051882 A136002

Adjacent sequences: A183220 A183221 A183222 * A183224 A183225 A183226

Keyword

nonn

Author

Clark Kimberling, Jan 01 2011

Status

approved