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 A030458 Primes formed by concatenating n with n+1. 33
 23, 67, 89, 1213, 3637, 4243, 5051, 5657, 6263, 6869, 7879, 8081, 9091, 9293, 9697, 102103, 108109, 120121, 126127, 138139, 150151, 156157, 180181, 186187, 188189, 192193, 200201, 216217, 242243, 246247, 252253, 270271 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes in A030656. LINKS Paul Tek, Table of n, a(n) for n = 1..10000 MAPLE P:=proc(i) local a, n; for n from 0 by 1 to i do a:=n*10^(trunc(evalf(log10(n+1)+1)))+n+1; if isprime(a) then print(a); fi; od; end: P(1000); # Paolo P. Lava, Oct 01 2008 MATHEMATICA Select[Table[FromDigits[Join[Flatten[IntegerDigits[{n, n+1}]]]], {n, 270}], PrimeQ] (* Jayanta Basu, May 16 2013 *) PROG (MAGMA) [m: n in [2..270 by 2] | IsPrime(m) where m is Seqint(Intseq(n+1) cat Intseq(n))];  // Bruno Berselli, Jun 18 2011 (PARI) forstep(n=2, 1e3, 2, if(isprime(k=eval(Str(n, n+1))), print1(k", "))) \\ Charles R Greathouse IV, Jun 18 2011 CROSSREFS Cf. A052089, A052087, A052088. Sequence in context: A059241 A241212 A052087 * A053559 A322414 A031376 Adjacent sequences:  A030455 A030456 A030457 * A030459 A030460 A030461 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified January 21 22:22 EST 2021. Contains 340356 sequences. (Running on oeis4.)