A183856 n+floor(sqrt(3n-2)); complement of A143975.

2, 4, 5, 7, 8, 10, 11, 12, 14, 15, 16, 17, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 102, 103, 104, 105, 106

Offset: 1

Author

Clark Kimberling, Jan 07 2011

Keywords

• nonn
• easy

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000212, A143975.

Programs

Maple

seq(seq(i+k,i=ceil((k^2+2)/3) .. ((k+1)^2+1)/3),k=1..10); # Robert Israel, Jun 04 2019

Mathematica

Array[#+Floor[Sqrt[3#-2]]&,100] (* Harvey P. Dale, Mar 15 2013 *)

Formula

a(n+1) - a(n) = 2 if n is in A000212, 1 otherwise. - Robert Israel, Jun 04 2019