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A032705 Numbers k such that k prefixed by '5' and followed by '1' is prime. 0
2, 4, 7, 10, 17, 23, 26, 28, 35, 38, 43, 44, 47, 50, 52, 53, 58, 59, 64, 65, 70, 71, 74, 79, 80, 82, 85, 86, 88, 98, 100, 103, 106, 107, 113, 115, 124, 134, 136, 142, 143, 146, 148, 151, 152, 155, 158, 163, 169, 172, 187, 194, 197, 199, 202, 205, 208, 212 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..58.

MATHEMATICA

Select[Range[0, 212], PrimeQ@FromDigits[Join[{5}, IntegerDigits@#, {1}]]&] (* Giorgos Kalogeropoulos, Jul 28 2021 *)

CROSSREFS

Subsequence of A001651 (not divisible by 3).

Sequence in context: A131752 A062365 A049630 * A332639 A281168 A274352

Adjacent sequences:  A032702 A032703 A032704 * A032706 A032707 A032708

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, May 15 1998

STATUS

approved

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Last modified October 21 05:28 EDT 2021. Contains 348141 sequences. (Running on oeis4.)