A121609 Composite numbers that can be written as concatenation of two primes in decimal representation.

22, 25, 27, 32, 33, 35, 52, 55, 57, 72, 75, 77, 112, 115, 117, 132, 133, 135, 172, 175, 177, 192, 195, 213, 217, 219, 231, 232, 235, 237, 243, 247, 253, 259, 261, 267, 273, 279, 289, 292, 295, 297, 312, 315, 319, 323, 329, 341, 343, 361, 371, 372, 375, 377

Offset: 1

Author

Reinhard Zumkeller, Aug 10 2006

Keywords

• nonn
• base

Comments

Subsequence of A066737.

Examples

			A002808(249) = 315 = 31*10+5 = A000040(11)*10+A000040(3),
therefore 315 is a term: a(44) = 315;
A002808(252) = 319 = 3*100+19 = A000040(2)*100+A000040(8),
therefore 319 is a term: a(45) = 319.
		

Links

• Jean-Marc Falcoz, Table of n, a(n) for n = 1..11140

Crossrefs

Cf. A121610, A105184, A121608.