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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
OFFSET
1,1
LINKS
EXAMPLE
57 is a term as tau(57) = 4 and 57-4 = 53 and 57+4 = 61 are both primes.
PROG
(PARI) isok(n) = my(nd = numdiv(n)); isprime(n-nd) && isprime(n+nd); \\ Michel Marcus, Oct 12 2018
CROSSREFS
Intersection of A067531 and A067532.
Sequence in context: A147426 A100437 A339567 * A110343 A146060 A076843
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Feb 17 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 19 2002
Offset corrected by Alois P. Heinz, Oct 10 2018
Name changed by David A. Corneth, Oct 12 2018
STATUS
approved