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

1,1

Links

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

Formula

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

Example

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

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 *)

Prog

(Sage)
[x for x in [1..100] if not(is_square(x)) and not(is_triangular_number(x))] # Tom Edgar, May 13 2014
(Haskell)
a242401 n = a242401_list !! (n-1)
a242401_list = filter ((== 0) . a010054) a000037_list
-- Reinhard Zumkeller, May 13 2014

Crossrefs

Cf. A000217, A000290.

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

Sequence in context: A160530 A214518 A331866 * A050941 A299232 A153083

Adjacent sequences: A242398 A242399 A242400 * A242402 A242403 A242404

Keyword

nonn,easy

Author

J. Lowell, May 13 2014

Status

approved