A121893 Composite integers not equal to k*[k or k+1 or k+2] where k is a natural number.

10, 14, 18, 21, 22, 26, 27, 28, 32, 33, 34, 38, 39, 40, 44, 45, 46, 50, 51, 52, 54, 55, 57, 58, 60, 62, 65, 66, 68, 69, 70, 74, 75, 76, 77, 78, 82, 84, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 98, 102, 104, 105, 106, 108, 111, 112, 114, 115, 116, 117, 118, 119, 122

Offset

1,1

Links

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

Maple

N:= 300: # for terms <= N
km:= floor(sqrt(N)):
sort(convert(remove(isprime, {$4..N}) minus {seq(k^2, k=1..km), seq(k*(k+1), k=1..km), seq(k*(k+2), k=1..km)}, list)); # Robert Israel, Mar 31 2026

Crossrefs

Cf. A308874, A000290, A002378, A005563.

Sequence in context: A250403 A096851 A244033 * A395791 A329390 A250197

Adjacent sequences: A121890 A121891 A121892 * A121894 A121895 A121896

Keyword

easy,nonn

Author

Giovanni Teofilatto, Sep 01 2006

Extensions

Incorrect term 80 removed by Michel Marcus, Mar 26 2022

Status

approved