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A134428 Primes formed by concatenating k with k+1, where k+1 is a prime. 1
23, 67, 1213, 3637, 4243, 7879, 9697, 102103, 108109, 126127, 138139, 150151, 156157, 180181, 192193, 270271, 276277, 312313, 330331, 378379, 420421, 432433, 438439, 456457, 522523, 540541, 546547, 576577, 600601, 606607, 612613, 618619 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Subset of A030458 and A052087.
LINKS
MAPLE
P:=proc(n) local a;
a:=(ithprime(n)-1)*10^(ilog10(ithprime(n))+1)+ithprime(n);
if isprime(a) then a; fi; end: seq(P(i), i=1..10^3);
MATHEMATICA
Select[Table[(p-1)*10^IntegerLength[p]+p, {p, Prime[Range[200]]}], PrimeQ] (* Harvey P. Dale, Aug 23 2019 *)
CROSSREFS
Sequence in context: A276262 A078622 A280376 * A195039 A042036 A042034
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)