A032614 -id:A032614 - cp's OEIS frontend

A032624 Numbers k such that k concatenated with k+9 is a prime.

2, 10, 14, 20, 28, 38, 40, 50, 52, 58, 62, 64, 70, 80, 82, 100, 104, 110, 112, 118, 122, 124, 142, 148, 160, 164, 170, 172, 178, 188, 194, 208, 218, 224, 230, 238, 244, 248, 250, 260, 262, 274, 284, 292, 298, 308, 320, 338, 344, 352, 362, 364, 382, 398, 400

Offset: 1

Patrick De Geest, May 15 1998

Robert Israel, Table of n, a(n) for n = 1..10000

Cf. A032614.

tcat:= (a,b) -> a*10^(1+ilog10(b))+b:
select(t -> isprime(tcat(t,t+9)), [seq(i,i=2..1000,2)]); # Robert Israel, Sep 04 2024

Select[Range[400],PrimeQ[FromDigits[Join[IntegerDigits[#],IntegerDigits[#+9]]]]&] (* Stefano Spezia, Sep 04 2023 *)

A032632 Primes that are decimal concatenations of n with n + 9.

Original entry on oeis.org

211, 1019, 1423, 2029, 2837, 3847, 4049, 5059, 5261, 5867, 6271, 6473, 7079, 8089, 8291, 100109, 104113, 110119, 112121, 118127, 122131, 124133, 142151, 148157, 160169, 164173, 170179, 172181, 178187, 188197, 194203, 208217

Offset: 1

Patrick De Geest, May 15 1998

Harvey P. Dale, Table of n, a(n) for n = 1..2500

Cf. A032614, A032624.

Select[Table[FromDigits[Flatten[IntegerDigits/@{n,n+9}]],{n,250}],PrimeQ] (* Harvey P. Dale, May 12 2019 *)

Edited by Charles R Greathouse IV, Apr 30 2010

cp's OEIS Frontend

A032624 Numbers k such that k concatenated with k+9 is a prime.

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