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 A290407 Primes obtained from other primes by prefixing an 8. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Except a(1), all the terms in this sequence are congruent to 1 mod 3. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 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. Cf. A165555, A167187, A289866, A289867. Sequence in context: A212379 A059935 A069596 * A112766 A128950 A068851 Adjacent sequences:  A290404 A290405 A290406 * A290408 A290409 A290410 KEYWORD nonn,base AUTHOR K. D. Bajpai, Jul 30 2017 STATUS approved

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Last modified February 26 02:19 EST 2020. Contains 332270 sequences. (Running on oeis4.)