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A064975
Numbers n such that n*10-1, n*10-3, n*10-7 and n*10-9 are all prime.
2
2, 11, 20, 83, 149, 188, 209, 326, 347, 566, 944, 1301, 1565, 1574, 1607, 1805, 1892, 1943, 2102, 2228, 2531, 3173, 3485, 4379, 5135, 5534, 6299, 6722, 6950, 7223, 7727, 7970, 8105, 8273, 8882, 9785, 9914, 10112, 10985, 11654, 11930, 12221, 13547
OFFSET
1,1
MATHEMATICA
Select[Range[10^5], PrimeQ[10# - 1] && PrimeQ[10# - 3] && PrimeQ[10# - 7] && PrimeQ[10# - 9] &]
CROSSREFS
Sequence in context: A279772 A226416 A146087 * A115095 A341003 A061907
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Oct 30 2001
STATUS
approved