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A290407
Primes obtained from other primes by prefixing an 8.
2
83, 811, 823, 829, 853, 859, 883, 8101, 8167, 8179, 8191, 8233, 8263, 8269, 8293, 8311, 8317, 8353, 8389, 8419, 8431, 8443, 8461, 8467, 8521, 8563, 8599, 8641, 8647, 8677, 8719, 8761, 8821, 8839, 8863, 8887, 8929, 8941, 8971, 81013, 81019, 81031, 81049, 81097
OFFSET
1,1
COMMENTS
Except a(1), all the terms in this sequence are congruent to 1 mod 3.
LINKS
EXAMPLE
823 is in the sequence because it is a prime obtained by prefixing an 8 to the prime 23.
8317 is in the sequence because it is a prime obtained by prefixing an 8 to the prime 317.
MAPLE
A290407:= n-> (parse(cat(8, ithprime(n)))): select(isprime, [seq((A290407 (n), n=1..1000))]);
MATHEMATICA
Select[k = 8; Table[FromDigits[Join[IntegerDigits[k], IntegerDigits[Prime[n]]]], {n, 500}], PrimeQ]
PROG
(PARI) forprime(p = 2, 5000, k=eval(concat(8, Str(p))); if(isprime(k), print1(k, ", ")));
(Magma) [k : p in PrimesUpTo (5000) | IsPrime (k) where k is Seqint (Intseq (p) cat Intseq (8))];
CROSSREFS
Subsequence of A045714.
Sequence in context: A212379 A059935 A069596 * A112766 A128950 A068851
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Jul 30 2017
STATUS
approved