OFFSET
1,1
COMMENTS
Records: 3, 5, 13, 19, 43, 79, 89, 107, 239, 269, 421, 523, 647, 929, 1069, 1321, 1783, 1879, 2347, 4217, 4801, 7001, 7691, 9623, 22769, 23011, 27541, 29009, ..., .
Position of the n_th prime: 2, 1, 3, 5, 6, 4, 11, 7, 14, 17, 10, 31, 15, 8, 42, 22, 21, 27, 16, 12, 18, 9, ..., .
Prime index of a(n): 2, 1, 3, 6, 4, 5, 8, 14, 22, 11, 7, 20, 24, 9, 13, 19, 10, 21, 23, 28, 17, 16, 52, 26, 29, 51, ..., .
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..1000
FORMULA
3*2*5*...*a(n) -1 is prime. a(n) is the least prime not previously in the sequence.
MATHEMATICA
f[s_List] := Block[{p = Times @@ s, q = 2}, While[ MemberQ[s, q] || !PrimeQ[p*q - 1], q = NextPrime@ q]; Append[s, q]]; Nest[f, {3}, 40]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jul 31 2017
STATUS
approved