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A123359
Least m such that 3^n+2^m is prime.
5
0, 1, 1, 1, 1, 3, 2, 4, 1, 2, 1, 6, 4, 3, 1, 1, 11, 6, 7, 21, 3, 8, 2, 5, 1, 7, 1, 4, 12, 11, 2, 4, 7, 10, 15, 6, 1, 30, 3, 8, 11, 11, 2, 6, 3, 16, 14, 17, 17, 4, 18, 50, 36, 6, 71, 6, 29, 2, 11, 6, 4, 16, 18, 1, 8, 6, 17, 9, 15, 14, 54, 12, 17, 12, 41, 4, 29, 3, 7, 25, 11, 35, 23, 24, 31, 27, 18
OFFSET
0,6
LINKS
EXAMPLE
a(0)=0 because 3^0+2^0=1+1=2 is prime,
a(5)=3 because 3^5+2^3=243+8=251 is prime.
MATHEMATICA
lm[n_]:=Module[{c=3^n, m=0}, While[!PrimeQ[c+2^m], m++]; m]; Array[lm, 90, 0] (* Harvey P. Dale, May 01 2013 *)
CROSSREFS
Cf. A123340 = least m such that 2^n+3^m is prime, A123342 = least m such that 2^n+5^m is prime.
Sequence in context: A097673 A226377 A140430 * A376070 A121885 A187760
KEYWORD
nonn
AUTHOR
Zak Seidov, Oct 12 2006
STATUS
approved