A214617 Primes written in the factorial base.

10, 11, 21, 101, 121, 201, 221, 301, 321, 1021, 1101, 1201, 1221, 1301, 1321, 2021, 2121, 2201, 2301, 2321, 3001, 3101, 3121, 3221, 4001, 4021, 4101, 4121, 4201, 4221, 10101, 10121, 10221, 10301, 11021, 11101, 11201, 11301, 11321, 12021, 12121, 12201, 12321

Offset: 1

Author

Jon Perry, Mar 06 2013

Keywords

• nonn
• base

Comments

The factorial base system uses 1!, 2!, 3!, ..., n! instead of powers of b, b^0, b^1, b^2, ... for some base b.

To be consistent with the normal base 10 system, the largest factorial used appears on the left.

Examples

			prime(6) = 13 = 2*3! + 1! so a(6) = 201.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A007623.

Programs

Maple

b:= proc(n, i) local r; `if`(n b(ithprime(n), 2):
seq(a(n), n=1..50);  # Alois P. Heinz, Mar 16 2013

Formula

a(n) = A007623(A000040(n)).