A093906 Start with {2} and close under the operations XY and XY+1; sequence gives complete list of numbers that do not appear.

1, 3, 6, 7, 12, 13, 14, 15, 24, 27, 28, 29, 30, 31, 48, 49, 54, 57, 58, 59, 60, 61, 62, 63, 97, 98, 108, 109, 114, 117, 118, 119, 120, 123, 124, 127, 194, 197, 217, 218, 219, 228, 229, 237, 238, 239, 240, 241, 246, 247, 248, 249, 389, 394, 434, 439, 457, 458, 479, 482, 492, 493, 497, 498, 499, 788, 789, 878, 879, 917, 959, 984, 985, 986, 994, 997, 998, 1579, 1757, 1758, 1759, 1968, 1971, 1988, 1994, 1997, 3514, 3517, 3518, 3989, 7028, 7034, 7037, 7978, 14074, 28148

Offset: 1

Author

Franklin T. Adams-Watters, May 25 2004

Keywords

• nonn
• fini
• full

Comments

If we start with {2} and close under the operations XY-1 and XY+1, we get the complement of A014574 (midpoints of twin primes), except for the absence of 1.

Crossrefs

Cf. A009388 and A009293.

Extensions

Corrected by Don Reble, May 25 2004