

A068526


Numbers n such that prime(n+1)prime(n) = tau(n) = A000005(n).


4



1, 2, 3, 5, 6, 7, 8, 13, 14, 17, 18, 22, 24, 27, 32, 38, 41, 43, 65, 76, 80, 83, 85, 89, 93, 95, 109, 113, 122, 128, 134, 135, 143, 155, 159, 164, 173, 180, 183, 186, 188, 213, 226, 235, 237, 243, 245, 246, 247, 248, 249, 254, 275, 277, 284, 287, 292, 301, 303
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OFFSET

1,2


LINKS

R. J. Mathar, Table of n, a(n) for n = 1..10159


EXAMPLE

1 has 1 divisor, prime(1) is 2, and 2+1=3 is prime(1+1), so 1 is in the sequence.
2 has 2 divisors, prime(2) is 3, and 3+2=5 is prime(2+1), so 2 is in the sequence.


MAPLE

with(numtheory): A068526:=n>`if`(ithprime(n+1)ithprime(n)=tau(n), n, NULL): seq(A068526(n), n=1..500); # Wesley Ivan Hurt, Apr 10 2015


CROSSREFS

Sequence in context: A028229 A104452 A062877 * A287339 A039086 A280060
Adjacent sequences: A068523 A068524 A068525 * A068527 A068528 A068529


KEYWORD

easy,nonn


AUTHOR

Benoit Cloitre, Mar 21 2002


STATUS

approved



