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A198519
a(2n-1) is the first unused prime which is the sum of the two preceding terms and such that a(2n) is that sum and it is also an unused prime.
1
3, 5, 11, 19, 7, 37, 17, 61, 23, 101, 13, 137, 29, 179, 31, 239, 41, 311, 67, 419, 71, 557, 73, 701, 47, 821, 43, 911, 59, 1013, 79, 1151, 53, 1283, 97, 1433, 83, 1613, 127, 1823, 89, 2039, 109, 2237, 113, 2459, 139, 2711, 103, 2953, 107, 3163, 163, 3433, 131, 3727, 149, 4007, 181, 4337, 173, 4691
OFFSET
1,1
LINKS
EXAMPLE
a(3) does not equal 7 since 3+5+7 which is 15 is not a prime, but the next prime, 11, meets the criteria.
MATHEMATICA
s = {3, 5}; k = 1; While[k < 31, p = s[[-2]] + s[[-1]]; q = 7; While[ !PrimeQ[p + q] || MemberQ[s, q] || MemberQ[s, p + q], q = NextPrime@ q]; AppendTo[s, q]; AppendTo[s, p + q]; k++]; s
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Dec 21 2012
STATUS
approved