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A241569
Primes of the form: (concatenation of first n positive integers) + 1.
2
2, 13, 123457, 123456789101112131415161718192021222324252627282931
OFFSET
1,1
COMMENTS
a(5) = 123...868788+1 (a 167-digit number). - Jon E. Schoenfield, Apr 26 2014
LINKS
EXAMPLE
123457 is in sequence because 123456+1 = 123457 is prime.
MATHEMATICA
Select[Table[FromDigits[Flatten[IntegerDigits[Range[n]]]] + 1, {n, 1, 1000}], PrimeQ] (* Bruno Berselli, Apr 27 2014 *)
PROG
(Magma) c:=0; for d in [1..3] do m:=10^d; for n in [m div 10..m-1] do c:=c*m+n; t:=c+1; if IsPrime(t) then t; end if; end for; end for; // Jon E. Schoenfield, Apr 26 2014
(Magma) [t+1: n in [1..1000] | IsPrime(t+1) where t is Seqint(Reverse(&cat[Reverse(Intseq(k)): k in [1..n]]))]; // Bruno Berselli, Apr 27 2014
CROSSREFS
Cf. A241570.
Sequence in context: A280798 A118912 A027680 * A262299 A135970 A027738
KEYWORD
nonn,base
AUTHOR
Vincenzo Librandi, Apr 26 2014
STATUS
approved