A109944 a(1) = 1, a(n) = smallest prime number beginning with n if n is composite or vice versa. If n is prime a(n) = 10n.

1, 20, 30, 41, 50, 61, 70, 83, 97, 101, 110, 127, 130, 149, 151, 163, 170, 181, 190, 2003, 211, 223, 230, 241, 251, 263, 271, 281, 290, 307, 310, 3203, 331, 347, 353, 367, 370, 383, 397, 401, 410, 421, 430, 443, 457, 461, 470, 487, 491, 503, 5101, 521, 530, 541

Offset: 1

Author

Amarnath Murthy, Jul 19 2005

Keywords

• base
• easy
• nonn

Comments

If n is composite, a(n) = A018800(n). - David Wasserman, Jul 19 2005

Extensions

More terms from David Wasserman, Jul 19 2005