A280636 Semiprime numbers whose digit string can be partitioned into three parts such that the product of the first two parts equals the third part.

111, 122, 133, 155, 166, 177, 326, 339, 515, 717, 818, 2918, 3721, 5315, 6742, 7214, 7642, 9327, 9763, 11111, 11333, 11555, 12929, 13333, 13535, 13565, 13791, 13939, 14114, 14141, 14242, 14545, 15115, 15151, 15353, 15454, 15757, 16161, 16565

Offset: 1

Author

Randy L. Ekl, Jan 06 2017

Keywords

• nonn
• base

Comments

Could be called semiprime area numbers. If the first set of digits of the number is considered the length, the second set of digits of the number is considered the width, and the final set of digits of the number is considered the area, then length * width = area.

Examples

			2918 is semiprime (2*1459) and an area number (2*9 = 18).
6742 is semiprime (2*3371) and an area number (6*7 = 42).
Leading zeros are not allowed.
		

Crossrefs

Cf. A088294, A280635.

Formula

A001358 INTERSECT A280635.