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A346043
a(n) is the position of A138534(n) in A025487.
2
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
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
Similar sequences: A098718, A098719, A293635, A306802.
Sequence in context: A150038 A150039 A150040 * A079456 A264761 A253882
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Jul 02 2021
EXTENSIONS
a(20)-a(21) from Jinyuan Wang, Jul 08 2021
STATUS
approved