A068703 Primes in the concatenation n,n+1, n+2, n+1, n.

34543, 1718191817, 2324252423, 3334353433, 3940414039, 7778797877, 8788898887, 123124125124123, 153154155154153, 159160161160159, 173174175174173, 207208209208207, 227228229228227, 279280281280279

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

1718191817 is a term as the concatenation of 17,18,19,18 and 17.

Maple

for n from 1 to 1500 do a := n+10^( floor(evalf(log(n)/log(10))+0.0000000001 )+1)*(n+1); a := a+10^( floor(evalf(log(a)/log(10))+0.0000000001 )+1)*(n+2); a := a+10^( floor(evalf(log(a)/log(10))+0.0000000001 )+1)*(n+1); a := a+10^( floor(evalf(log(a)/log(10))+0.0000000001 )+1)*n; b[n] := a:end do:k := 0:for n from 2 to 1500 doif(isprime(b[n]) ) then k := k+1:c[k] := b[n]:end if:end do:seq(c[j], j=1..k);

Mathematica

Select[Table[FromDigits[Flatten[{IntegerDigits[n], IntegerDigits[n+1], IntegerDigits[n+2], IntegerDigits[n+1], IntegerDigits[n], {}}]], {n, 1000}], PrimeQ] (* Vincenzo Librandi, Mar 13 2013 *)

Prog

(Magma) [m: n in [1..300] | IsPrime(m) where m is Seqint([] cat Intseq(n) cat Intseq(n+1) cat Intseq(n+2) cat Intseq(n+1) cat Intseq(n))]; // Vincenzo Librandi, Mar 13 2013

Crossrefs

Sequence in context: A055001 A164556 A344780 * A225025 A081428 A237955

Adjacent sequences: A068700 A068701 A068702 * A068704 A068705 A068706

Keyword

nonn,base

Author

Amarnath Murthy, Mar 04 2002

Extensions

More terms from Sascha Kurz, Mar 27 2002

Status

approved