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A154963 Primes n such that concatenation of n and n-th prime is prime. 2
2, 17, 23, 41, 61, 71, 83, 127, 227, 337, 353, 499, 503, 571, 727, 887, 911, 937, 971, 1061, 1427, 1579, 1663, 1693, 1709, 1871, 1877, 1907, 1949, 1973, 2017, 2063, 2081, 2239, 2339, 2393, 2467, 2713, 2797, 2939, 2999, 3181, 3271, 3463, 3643, 3659, 3677 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

Concatenation of prime 2 and second prime 3 is the prime 23, hence 2 is in the sequence. Concatenation of prime 23 and 23rd prime 83 is the prime 2383, hence 23 is in the sequence.

MATHEMATICA

A154963 = Select[ Prime[ Range[ 550 ] ], PrimeQ[ FromDigits[ Join[ IntegerDigits[ # ], IntegerDigits[ Prime[ # ] ] ] ] ] & ] (* >From Alonso del Arte Nov 12 2009 *)

PROG

(MAGMA) [ p: p in PrimesUpTo(3700) | IsPrime(StringToInteger(IntegerToString(p) cat IntegerToString(NthPrime(p)))) ];

CROSSREFS

For the primes indexed by these concatenations, see A155032. In other words, A000040(a(n)) = A155032.

Sequence in context: A094668 A019421 A105901 * A049562 A107137 A086322

Adjacent sequences:  A154960 A154961 A154962 * A154964 A154965 A154966

KEYWORD

nonn,base,easy,less

AUTHOR

Juri-Stepan Gerasimov, Jan 18 2009

EXTENSIONS

Edited and extended beyond a(3) by Klaus Brockhaus, Jan 20 2009

STATUS

approved

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Last modified April 20 08:50 EDT 2019. Contains 322306 sequences. (Running on oeis4.)