A046423 Numbers requiring 3 steps to reach a prime under the prime factor concatenation procedure.

25, 35, 56, 62, 69, 72, 76, 85, 90, 100, 114, 125, 138, 143, 152, 189, 213, 221, 238, 250, 259, 260, 270, 275, 278, 303, 318, 333, 364, 366, 369, 390, 403, 441, 448, 454, 469, 470, 473, 485, 507, 512, 519, 522, 529, 559, 560, 572, 588, 591, 624, 629, 648

Offset

1,1

Links

Table of n, a(n) for n=1..53.

Patrick De Geest, Home Primes

Example

69 = 3*23 -> 323 = 17*19 -> 1719 = 3*3*191 and 33191 is prime.

Crossrefs

Cf. A037271, A046411.

Sequence in context: A276290 A173251 A063149 * A347612 A331808 A153446

Adjacent sequences: A046420 A046421 A046422 * A046424 A046425 A046426

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Extensions

Edited by Charles R Greathouse IV, Apr 28 2010

Status

approved