A131181 A 2-way classification of integers: complement of A026416.

6, 8, 10, 12, 14, 15, 18, 20, 21, 22, 26, 27, 28, 32, 33, 34, 35, 36, 38, 39, 44, 45, 46, 48, 50, 51, 52, 55, 57, 58, 60, 62, 63, 64, 65, 68, 69, 72, 74, 75, 76, 77, 80, 82, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 106, 108, 111, 112, 115, 116, 117, 118, 119, 120, 122, 123, 124, 125, 126, 129, 132, 133, 134, 140, 141, 142, 143, 144, 145, 146, 147, 148, 150, 153, 155, 156, 158, 159, 160, 161, 162, 164, 166, 168, 171, 172, 175, 176, 177, 178, 183

Offset: 1

Author

Max Alekseyev, Sep 23 2007

Keywords

• nonn
• easy

Comments

The sequence contains (for example) 140, so differs from A000379 by more than just the missing term 1. - Vladimir Shevelev, Apr 05 2013

Crossrefs

Complement of A026416.

Cf. A000379.

Programs

Mathematica

f[1]=1; f[2]=2; f[n_] := f[n] = For[k = f[n-1]+1, True, k++, If[ FreeQ[ Table[ f[i]*f[j], {i, 1, n-2}, {j, i+1, n-1}], k], Return[k]]];
A026416 = Table[f[n], {n, 1, 80}];
A131181 = Complement[ Range[ A026416 // Last], A026416] (* Jean-François Alcover, May 16 2013 *)