A256176 Primes formed by concatenating n with n+1 and by concatenating n+2 with n+3.

67, 89, 7879, 8081, 9091, 9293, 186187, 188189, 276277, 278279, 426427, 428429, 438439, 440441, 450451, 452453, 600601, 602603, 606607, 608609, 798799, 800801, 816817, 818819, 858859, 860861, 936937, 938939, 960961, 962963, 11401141, 11421143

Offset

1,1

Comments

Subsequence of A030458.

First bisection: A156121.

Links

Bui Quang Tuan, Table of n, a(n) for n = 1..100

Example

67, 89 are in the sequence because they are primes and 6, 7, 8, 9 are four consecutive integers.
7879, 8081 are in the sequence because they are primes and 78, 79, 80, 81 are four consecutive integers.
186187, 188189 are in the sequence because they are primes and 186, 187, 188, 189 are four consecutive integers.

Mathematica

f[n_] := FromDigits@ Flatten[IntegerDigits /@ Range[n, n + 1]]; {f@ #, f[# + 2]} & /@ Select[Range@ 1200, AllTrue[{f@ #, f[# + 2]}, PrimeQ] &] // Flatten (* Michael De Vlieger, Mar 18 2015 *)
fd[{a_, b_}]:=FromDigits[Join[IntegerDigits[a], IntegerDigits[b]]]; Select[ {fd[ Take[#, 2]], fd[Take[#, -2]]}&/@Partition[Range[1500], 4, 1], AllTrue[ #, PrimeQ]&]//Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 17 2018 *)

Prog

(PARI) lista(nn) = {for (n=1, nn, if (isprime(p=eval(concat(Str(n), Str(n+1)))) && isprime(q=eval(concat(Str(n+2), Str(n+3)))), print1(p, ", ", q, ", ")); ); } \\ Michel Marcus, Mar 18 2015

Crossrefs

Sequence in context: A119893 A130059 A039539 * A158848 A232634 A302345

Adjacent sequences: A256173 A256174 A256175 * A256177 A256178 A256179

Keyword

nonn,base

Author

Bui Quang Tuan, Mar 18 2015

Status

approved