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A256176
Primes formed by concatenating n with n+1 and by concatenating n+2 with n+3.
1
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
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
KEYWORD
nonn,base
AUTHOR
Bui Quang Tuan, Mar 18 2015
STATUS
approved