A087558 a(n) = largest prime that is the concatenation of two numbers whose product is n.

11, 0, 31, 41, 0, 61, 71, 0, 19, 101, 0, 43, 131, 0, 151, 0, 0, 181, 191, 0, 211, 211, 0, 241, 251, 0, 271, 281, 0, 103, 311, 0, 331, 0, 0, 0, 137, 0, 313, 401, 0, 421, 431, 0, 59, 461, 0, 163, 491, 0, 317, 521, 0, 541, 0, 0, 571, 229, 0, 601, 0, 0, 631, 641, 0, 661, 167, 0, 691

Offset

2,1

Comments

a(3k+2) = 0. - David Wasserman, Jun 07 2005

Links

Table of n, a(n) for n=2..70.

Example

a(10) = 101, the pair of complementary factors of 10 are (1,10), (2,5) and the prime obtained is 101.

Crossrefs

Cf. A087557.

Sequence in context: A274851 A075360 A256756 * A087555 A185682 A217752

Adjacent sequences: A087555 A087556 A087557 * A087559 A087560 A087561

Keyword

base,nonn

Author

Amarnath Murthy, Sep 13 2003

Extensions

More terms from David Wasserman, Jun 07 2005

Status

approved