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A165555
Primes obtained from other primes by prefixing a 5.
5
53, 523, 541, 547, 571, 5101, 5107, 5113, 5167, 5179, 5197, 5227, 5233, 5281, 5347, 5419, 5431, 5443, 5449, 5479, 5503, 5521, 5557, 5563, 5569, 5641, 5647, 5653, 5659, 5683, 5701, 5743, 5821, 5827, 5839, 5857, 5881, 5953, 51031, 51061, 51109, 51151, 51193, 51217
OFFSET
1,1
COMMENTS
The primes are considered in increasing order. Primes with the same number of digits, the difference between adjacent terms seems to be a multiple of 3.
LINKS
EXAMPLE
5479 is a prime obtained by prefixing a 5 to the prime 479.
MAPLE
A165555:= n-> (parse(cat(5, ithprime(n)))): select(isprime, [seq((A165555(n), n=1..1000))]); # K. D. Bajpai, Jul 14 2017
MATHEMATICA
Select[Table[FromDigits[Join[IntegerDigits[5], IntegerDigits[Prime[n]]]], {n, 500}], PrimeQ] (*K. D. Bajpai, Jul 14 2017 *)
Select[5*10^IntegerLength[#]+#&/@Prime[Range[200]], PrimeQ] (* Harvey P. Dale, Sep 29 2024 *)
PROG
(Magma)[k : p in PrimesUpTo (2000) | IsPrime (k) where k is Seqint (Intseq (p) cat Intseq (5))]; // K. D. Bajpai, Jul 14 2017
(PARI) lista(nn) = forprime(p=2, nn, if (isprime(q=eval(concat(5, Str(p)))), print1(q, ", "))); \\ Michel Marcus, Jul 29 2017
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Parthasarathy Nambi, Sep 21 2009
EXTENSIONS
More terms from Vincenzo Librandi, Dec 02 2010
Missing term 5449 inserted by K. D. Bajpai, Jul 14 2017
STATUS
approved