login
A340587
a(n) is the least root of A340586(n).
3
2, 2, 13, 6, 7, 20, 21, 2, 5, 3, 29, 30, 34, 38, 39, 40, 12, 43, 44, 2, 7, 51, 14, 54, 5, 57, 15, 60, 61, 62, 2, 66, 67, 68, 69, 17, 72, 73, 74, 75, 18, 78, 79, 3, 19, 84, 85, 86, 87, 6, 20, 2, 92, 93, 94, 95, 21, 98, 10, 102, 22, 105, 106, 107, 108, 109, 23, 112
OFFSET
1,1
FORMULA
a(n) = A025478(A340586(n)).
EXAMPLE
a(1) = 2: A340586(1) = 4 = 2^2,
a(2) = 2: A340586(2) = 16 = 2^4,
a(3) = 13: A340586(3) = 169 = 13^2.
PROG
(PARI) a340587(limit)={my(p2=999, p1=2, n2=1, n1=4); for(n=5, limit, my(p0=ispower(n)); if(p0>1, if(p2+p0==4, print1(round(n1^(1/p1)), ", ")); n2=n1; n1=n; p2=p1; p1=p0))};
a340587(13000)
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Jan 14 2021
STATUS
approved