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A290282
Numbers k such that (32*10^k + 337)/9 is prime.
0
0, 1, 3, 4, 127, 144, 213, 219, 228, 463, 646, 846, 1308, 1402, 1419, 1594, 1806, 3442, 4798, 9616, 10471, 11916
OFFSET
1,3
COMMENTS
For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 5 followed by the digits 93 is prime (see Example section).
a(23) > 2*10^5.
EXAMPLE
3 is in this sequence because (32*10^3 + 337)/9 = 3593 is prime.
Initial terms and associated primes:
a(1) = 0, 41;
a(2) = 1, 73;
a(3) = 3, 3593;
a(4) = 4; 35593; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(32*10^# + 337)/9] &]
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Jul 25 2017
STATUS
approved