A259175 a(n) = 1 if n prime, otherwise prime(n).

2, 1, 1, 7, 1, 13, 1, 19, 23, 29, 1, 37, 1, 43, 47, 53, 1, 61, 1, 71, 73, 79, 1, 89, 97, 101, 103, 107, 1, 113, 1, 131, 137, 139, 149, 151, 1, 163, 167, 173, 1, 181, 1, 193, 197, 199, 1, 223, 227, 229, 233, 239, 1, 251, 257, 263, 269, 271, 1, 281, 1, 293, 307, 311

Offset

1,1

Comments

The subsequence of prime terms is A007821. - Michel Marcus, Jun 20 2015

Links

Table of n, a(n) for n=1..64.

Example

a(7) = 1 because 7 is prime.
a(8) = 19 because 8 is not prime and prime(8) = 19.

Mathematica

Table[If[PrimeQ[n], 1, Prime[n]], {n, 100}]

Prog

(Magma) [IsPrime(n) select 1 else NthPrime(n): n in [1..100]];

Crossrefs

Cf. A007821, A010051, A061397, A191558.

Sequence in context: A247450 A178234 A344440 * A297431 A346083 A301922

Adjacent sequences: A259172 A259173 A259174 * A259176 A259177 A259178

Keyword

nonn,easy

Author

Vincenzo Librandi, Jun 20 2015

Status

approved