A032666 -id:A032666 - cp's OEIS frontend

A032667 Digit '4' concatenated with a(n) is a prime.

1, 3, 7, 19, 21, 31, 33, 39, 43, 49, 57, 61, 63, 67, 79, 87, 91, 99, 111, 127, 129, 133, 139, 153, 157, 159, 177, 201, 211, 217, 219, 229, 231, 241, 243, 253, 259, 261, 271, 273, 283, 289, 297, 327, 337, 339, 349, 357, 363, 373, 391, 397, 409

Offset: 1

Patrick De Geest, May 15 1998

Obviously there can be no even terms in this sequence. - Alonso del Arte, Jun 18 2017

			Concatenate 4 and 1 to get 41, which is prime, so 1 is in the sequence.
Concatenate 4 and 3 to get 43, which is prime, so 3 is in the sequence.
Concatenate 4 and 5 to get 45 = 3^2 * 5, which is not prime, so 5 is not in the sequence.

Seiichi Manyama, Table of n, a(n) for n = 1..10000 (terms 1..1740 from Vincenzo Librandi)

Cf. other digit 'd' concatenated with a(n) is prime sequences: A032664 (d = 1), A032665 (d = 2), A032666 (d = 3), A032668 (d = 5), A032669 (d = 6), A032670 (d = 7), A032671 (d = 8), A032672 (d = 9), A000040 (d = 0).

Select[2Range[250] - 1, PrimeQ[FromDigits[Join[{4}, IntegerDigits[#]]]] &] (* Alonso del Arte, Jun 18 2017 *)

isok(n) = isprime(eval(concat(4, Str(n)))); \\ Michel Marcus, Jun 19 2017

Offset adjusted at the suggestion of Michel Marcus by Alonso del Arte, Jun 18 2017

A167727 Cubes that becomes a prime number when prefixed with a 3.

Original entry on oeis.org

1, 343, 4913, 226981, 389017, 456533, 571787, 912673, 1295029, 2352637, 5177717, 5735339, 7645373, 9129329, 10218313, 11089567, 19902511

Offset: 1

Claudio Meller, Nov 10 2009

Subsequence of cubes of A032666. - Michel Marcus, Jun 22 2016

G. C. Greubel, Table of n, a(n) for n = 1..10000

Cf. A032666.

a441 = Select[Range[1, 5000, 2]^3, PrimeQ[FromDigits[Join[{3}, IntegerDigits[#]]]] &] (* G. C. Greubel, Jun 21 2016 *)

A107073 Numbers k such that the string 35k is prime.

Original entry on oeis.org

3, 9, 11, 17, 27, 29, 33, 39, 41, 47, 57, 59, 71, 81, 83, 93, 107, 111, 117, 129, 141, 149, 153, 159, 171, 201, 221, 227, 251, 257, 267, 279, 281, 291, 311, 317, 323, 327, 339, 353, 363, 381, 393, 401, 407, 419, 423, 437, 447, 449, 461, 491, 507, 509, 521, 527

Offset: 1

Parthasarathy Nambi, Jun 07 2005

			If k=47 then 3547 is prime.

Cf. A032666. - R. J. Mathar, Jan 16 2009

[ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [5, 3])) ]; // Vincenzo Librandi, Feb 03 2011

A055642 := proc(n) max(1,ilog10(n)+1) ; end: cat2 := proc(a,b) a*10^A055642(b)+b ; end: for n from 1 to 1000 do if isprime( cat2(35,n) ) then printf("%d,",n) ; fi; od: # R. J. Mathar, Jan 16 2009

Select[Range[600],PrimeQ[FromDigits[Join[{3,5},IntegerDigits[#]]]]&] (* Harvey P. Dale, Jun 06 2015 *)

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A032667 Digit '4' concatenated with a(n) is a prime.

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A167727 Cubes that becomes a prime number when prefixed with a 3.

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A107073 Numbers k such that the string 35k is prime.

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