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%I #7 Jun 22 2019 10:10:34
%S -1,-1,12,22,34,49,68,90,117,147,180,219
%N Number of natural numbers that are not a sum of n distinct primes, or -1 if it is infinite.
%C A124884(n) = {-1, -1, 17, 30, 41, 60, 83, 102, 137, 162, 203, 244, ...} Largest number that is not a sum of n distinct primes, or -1 if such a number does not exist.
%C Natural numbers that are not the sum of 2 distinct primes are {1 - 4, 6, 11, 17, 23, 27, 29, 35, 37, 41, 47, ...}, complement to A038609(n)
%C Numbers that are the sum of 2 different primes.
%C Natural numbers that are not the sum of 3 distinct primes A124868(n) = {1 - 9, 11, 13, 17}.
%C Natural numbers that are not the sum of 4 distinct primes are {1 - 16, 18, 19, 20, 22, 24, 30}.
%C Natural numbers that are not the sum of 5 distinct primes are {1 - 27, 29, 31, 32, 33, 35, 37, 41}.
%C Natural numbers that are not the sum of 6 distinct primes are {1 - 40, 42, 43, 44, 46, 48, 50, 52, 54, 60}.
%C Natural numbers that are not the sum of 7 distinct primes are {1 - 57, 59, 61, 62, 63, 65, 67, 69, 71, 73, 77, 83}.
%C Natural numbers that are not the sum of 8 distinct primes are {1 - 76, 78, 79, 80, 82, 84, 85, 86, 88, 90, 92, 94, 96, 100, 102}.
%C Natural numbers that are not the sum of 9 distinct primes are {1 - 99, 101, 102, 103, 104, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 131, 133, 137}.
%C Natural numbers that are not the sum of 10 distinct primes are {1 - 128, 130, 132, 133, 134, 135, 136, 138, 139, 140, 142, 144, 146, 148, 150, 152, 154, 156, 160, 162}.
%C Natural numbers that are not the sum of 11 distinct primes are {1 - 159, 161, 162, 163, 164, 165, 167, 169, 171, 173, 175, 177, 179, 181, 183, 185, 187, 189, 191, 193, 197, 203}.
%C Natural numbers that are not the sum of 12 distinct primes are {1 - 196, 198, 199, 200, 202, 204, 205, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 240, 244}.
%e a(1) = -1 because there are an infinite number of nonprimes.
%e a(3) = 12 because 12 = Length[{1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 17}] = Length[A124868(n)], where A124868(n) are the natural numbers that are not the sum of 3 distinct primes.
%Y Cf. A000040, A038609, A124868, A124884.
%K more,sign
%O 1,3
%A _Alexander Adamchuk_, Nov 12 2006
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