

A163578


If n is prime, a(n) is next composite greater than a(n1), else if n is composite, a(n) is next prime greater than a(n1) else 2.


1



2, 4, 6, 7, 8, 11, 12, 13, 17, 19, 20, 23, 24, 29, 31, 37, 38, 41, 42, 43
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


LINKS

Table of n, a(n) for n=1..20.


EXAMPLE

1 is not prime, a(1)=2, 2 is prime, a(2)=4, 3 is prime, a(3)=6, 4 is composite, a(4)=7.


CROSSREFS

Cf. A159559
Sequence in context: A165778 A286066 A139527 * A269389 A092054 A334573
Adjacent sequences: A163575 A163576 A163577 * A163579 A163580 A163581


KEYWORD

nonn


AUTHOR

Gerald Hillier, Jul 31 2009


STATUS

approved



