

A067533


Numbers k such that both k  tau(k) and k + tau(k) are prime where tau(k) = A000005(k).


1



5, 15, 27, 33, 57, 93, 105, 165, 177, 189, 231, 237, 245, 267, 275, 285, 345, 375, 393, 425, 453, 555, 567, 573, 597, 609, 637, 651, 687, 723, 833, 933, 1005, 1025, 1095, 1167, 1209, 1221, 1227, 1293, 1311, 1431, 1445, 1479, 1491, 1527, 1551, 1563, 1573
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OFFSET

1,1


LINKS



EXAMPLE

57 is a term as tau(57) = 4 and 574 = 53 and 57+4 = 61 are both primes.


PROG

(PARI) isok(n) = my(nd = numdiv(n)); isprime(nnd) && isprime(n+nd); \\ Michel Marcus, Oct 12 2018


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



