A176589 Numbers n such that both concatenation of divisors of n and reverse concatenation of divisors of n are noncomposites.

1, 3, 7, 13, 31, 97, 103, 109, 151, 181, 193, 367, 409, 439, 487, 523, 571, 601, 613, 733, 811, 823, 1069, 1117, 1279, 1483, 1489, 1579, 1597, 1789, 1831, 1867, 1897, 1939, 2161, 2203, 2239, 2251, 2269, 2281, 2437, 2503, 2509, 2539, 2659, 2671, 2689, 2953

Offset

1,2

Comments

See A037278(n) = concatenation of divisors of n and A176558(n) = reverse concatenation of divisors of n. See A176553, A089374. Sequence of corresponding values of concatenations of divisors of a(n): {1, 13, 17, 113, 131, 197, ...), sequence of corresponding values of reverse concatenations of divisors of a(n): {1, 31, 71, 131, 311, 971, ...).

Links

Table of n, a(n) for n=1..48.

Example

a(5) = 31; divisors of 31: 1, 31; both concatenation of divisors 131 and reverse concatenation of divisors 311 are noncomposite.

Crossrefs

Sequence in context: A247895 A336688 A155128 * A077314 A069246 A340870

Adjacent sequences: A176586 A176587 A176588 * A176590 A176591 A176592

Keyword

nonn,base

Author

Jaroslav Krizek, Apr 21 2010

Extensions

Expanded and revised by Charles R Greathouse IV, Apr 24 2010

Status

approved