OFFSET
1,1
COMMENTS
Also prime numbers p whose index pi(p) is the Matula-Goebel number of a planted achiral tree.
An alternative definition: prime(n) is in the sequence iff n is a perfect power of a prime number already in the sequence.
FORMULA
a(1) = 2; a(n+1) = prime(A214577(n)).
EXAMPLE
a(n) = prime(Product_{i in y} a(i)) where y is the n-th partition in the following sequence, which spans all constant partitions: 1,2,11,3,4,111,22,5,1111,6,7,8,33,222,9,11111,44,...
MATHEMATICA
nn=10000;
BTQ[n_]:=Or[n===1, MatchQ[PrimePi/@FactorInteger[n][[All, 1]], {_?BTQ}]];
Prime/@Select[Range[PrimePi[nn]], BTQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 12 2017
STATUS
approved