

A255013


a(n) = the least semiprime such that n+a(n) is also semiprime.


0



9, 4, 6, 6, 4, 4, 14, 6, 6, 4, 4, 9, 9, 21, 6, 6, 4, 4, 6, 6, 4, 4, 10, 9, 9, 9, 6, 6, 4, 4, 4, 6, 6, 4, 4, 10, 9, 39, 10, 6, 10, 4, 6, 14, 4, 9, 4, 9, 6, 15, 4, 6, 4, 4, 10, 6, 25, 4, 6, 9, 4, 15, 6, 10, 4, 21, 10, 6, 22, 4, 6, 10, 4, 21, 10, 6, 9, 4, 6, 6, 4, 4, 4, 9, 6, 9, 4, 6, 4, 4, 4, 14
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OFFSET

1,1


COMMENTS

Corresponding values of n+a(n): 10,6,9,10,9,10,21,14,15,14,15,21,22,35,21.


LINKS

Table of n, a(n) for n=1..92.


EXAMPLE

a(1)=9 because 1+9=10=2*5, a(2)=4 because 2+4=6=2*3.


MATHEMATICA

Table[m=4; While[2!=PrimeOmega[m]2!=PrimeOmega[m+n], m++]; m, {n, 100}]


CROSSREFS

Cf. A001358.
Sequence in context: A194826 A309610 A198989 * A088539 A245084 A199054
Adjacent sequences: A255010 A255011 A255012 * A255014 A255015 A255016


KEYWORD

nonn


AUTHOR

Zak Seidov, Feb 12 2015


STATUS

approved



