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A109369
Numbers n such that the string 33n is the decimal expansion of a prime number.
2
1, 7, 13, 19, 23, 29, 31, 43, 47, 59, 61, 71, 73, 89, 91, 107, 113, 119, 149, 151, 161, 179, 181, 191, 199, 203, 211, 223, 247, 287, 289, 301, 311, 317, 329, 331, 343, 347, 349, 353, 359, 377, 391, 403, 409, 413, 427, 457, 461, 469, 479, 487, 493, 503, 521
OFFSET
1,2
LINKS
EXAMPLE
1 is in the sequence because 331 is prime.
59 is in the sequence because 3359 is prime.
107 is in the sequence because 33107 is prime.
MAPLE
a:=proc(n) if isprime(33*10^nops(convert(n, base, 10))+n)=true then n else fi end: seq(a(n), n=0..600); # Emeric Deutsch, Sep 02 2005
MATHEMATICA
Select[Range[600], PrimeQ[33*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jul 29 2014 *)
PROG
(Magma) [ n: n in [1..600] | IsPrime(Seqint(Intseq(n) cat [3, 3])) ];
CROSSREFS
Sequence in context: A007921 A092409 A124095 * A336373 A320629 A371166
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Aug 24 2005
EXTENSIONS
More terms from Emeric Deutsch, Sep 02 2005
STATUS
approved