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

0,2

Links

Table of n, a(n) for n=0..21.

Formula

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

Example

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

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

Prog

(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

Crossrefs

Cf. A025487, A138534.

Similar sequences: A098718, A098719, A293635, A306802.

Sequence in context: A150038 A150039 A150040 * A079456 A264761 A253882

Adjacent sequences: A346040 A346041 A346042 * A346044 A346045 A346046

Keyword

nonn,more

Author

Amiram Eldar, Jul 02 2021

Extensions

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

Status

approved