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.

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

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

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

Cf. A073653, A084331, A101595.

Sequence in context: A320351 A319641 A306895 * A045957 A364962 A153065

Adjacent sequences: A198516 A198517 A198518 * A198520 A198521 A198522

Keyword

easy,nonn

Author

Robert G. Wilson v, Dec 21 2012

Status

approved