A163398 Numbers m such that all numbers 10*m+(odd single-digit number) and 100*m+(any 2-digit, digits coprime to 10) are composite.

167, 176, 403, 513, 761, 935, 1037, 1218, 1307, 1559, 1865, 1932, 1995, 2057, 2123, 2255, 2288, 2340, 2414, 2852, 3152, 3483, 3581, 3734, 3914, 4136, 4169, 4226, 4238, 4265, 4373, 4390, 4433, 4436, 4443, 4460, 4466, 4482, 4631, 4706, 4806, 4842, 4850

Offset: 1

Author

Vladislav-Stepan Malakhovsky and Juri-Stepan Gerasimov, Jul 26 2009

Keywords

• nonn
• base
• less

Comments

The first requirement is that 10m+1, 10m+3, 10m+5, 10m+7 and 10m+9 are all composite; for 10*m+5 with the divisor 5 this is redundant. The second requirement is that 100*m plus any 2-digit number of A136333 is also composite.

Examples

			m=167 is in the sequence because 1671, 1673, 1677, 1679, 16711, 16713, 16717, 16719, 16731,
16733, 16737, 16739, 16771, 16773, 16777, 16779, 16791, 16793, 16797, 16799 are composites.
		

Crossrefs

Cf. A002808.

Extensions

Rephrased in terms of A136333 and extended by R. J. Mathar, Aug 02 2009