A242401 Numbers that are neither triangular nor square.

2, 5, 7, 8, 11, 12, 13, 14, 17, 18, 19, 20, 22, 23, 24, 26, 27, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 80, 82, 83, 84

Offset: 1

Author

J. Lowell, May 13 2014

Keywords

• nonn
• easy

Examples

			6 is not a term because it's triangular;
9 is not a term because it's square.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000217, A000290.

Cf. A005214 (complement); intersection of A000037 and A014132.

Programs

Haskell

a242401 n = a242401_list !! (n-1)
a242401_list = filter ((== 0) . a010054) a000037_list
-- Reinhard Zumkeller, May 13 2014

Mathematica

With[{nn=90},Complement[Range[nn],Range[Floor[Sqrt[nn]]]^2,Accumulate[ Range[ Floor[(Sqrt[1+8nn]-1)/2]]]]] (* Harvey P. Dale, May 03 2022 *)

Sage

[x for x in [1..100] if not(is_square(x)) and not(is_triangular_number(x))] # Tom Edgar, May 13 2014

Formula

A010052(a(n)) + A010054(a(n)) = 0. - Reinhard Zumkeller, May 13 2014