A346043 a(n) is the position of A138534(n) in A025487.

1, 2, 6, 17, 67, 166, 676, 1373, 4475, 10446, 30036, 51032, 196386, 315302, 737515, 1654229, 4227565, 6301902, 17975187, 26010425, 70085244, 133337963

Offset: 0

Author

Amiram Eldar, Jul 02 2021

Keywords

• nonn
• more

Examples

			A138534(2) = A025487(6) = 12, so a(2) = 6.
		

Crossrefs

Cf. A025487, A138534.

Similar sequences: A098718, A098719, A293635, A306802.

Programs

Mathematica

lps = Cases[Import["https://oeis.org/A025487/b025487.txt", "Table"], {, }][[;; , 2]]; s = {}; Do[p = Position[lps, Product[Prime[k]^Floor[n/k], {k, 1, n}]]; If[p == {}, Break[]]; AppendTo[s, p[[1, 1]]], {n, 0, 20}]; s

PARI

f(m) = my(c=1, p, q=2, v=vector(logint(m, 2), i, 2^i), w); while(#v, c+=#v; p=q; q=nextprime(q+1); w=List([]); for(i=1, #v, for(j=1, min(valuation(v[i], p), logint(m\v[i], q)), listput(w, v[i]*q^j))); v=w); c;
a(n) = f(prod(k=1, n, prime(k)^(n\k))); \\ Jinyuan Wang, Jul 08 2021

Formula

A025487(a(n)) = A138534(n).

Extensions

a(20)-a(21) from Jinyuan Wang, Jul 08 2021