A341416 a(n) is the least k such that the product of indices of unitary prime power divisors of k is n.

1, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 37, 35, 36, 47, 49, 40, 59, 61, 52, 45, 71, 56, 79, 55, 68, 89, 63, 65, 103, 107, 92, 77, 121, 72, 127, 85, 91, 137, 139, 88, 151, 112, 124, 115, 169, 104, 119, 99, 148, 193, 197, 133, 211, 223, 117, 145, 161, 136, 241, 155, 196

Offset

1,2

Comments

a(n) is the least k such that A333235(k) = n.

a(p) = A246655(p) for prime p.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

A333235(a(n)) = n.

Example

a(3) = 4 because A333235(4) = 3 and this is the first occurrence of 3 in A333235.

Maple

N:= 1000: # for a(1) to a(A025528(N))
R:= NULL: p:= 2:
while p < N do
  R:= R,  seq(p^k, k=1..ilog[p](N));
  p:= nextprime(p);
od:
L:= sort([R]):
M:= nops(L):
f:= proc(n) local F, t;
  F:= ifactors(n)[2];
  mul(ListTools:-BinarySearch(L, t[1]^t[2]), t=F)
end proc:
V:= Vector(M): count:= 0:
for n from 1 while count < M do
  v:= f(n);
if v <= M and V[v] = 0 then count:= count+1; V[v]:= n fi;
od:
convert(V, list);

Crossrefs

Cf. A246655, A333235.

Sequence in context: A354994 A214585 A196036 * A081376 A055074 A035059

Adjacent sequences: A341413 A341414 A341415 * A341417 A341418 A341419

Keyword

nonn,look

Author

Robert Israel, Feb 11 2021

Status

approved