A392345 - OEIS

A392345

Distinct terms of A007732 in the order in which they appear.

1, 6, 2, 16, 18, 22, 3, 28, 15, 5, 21, 46, 42, 13, 58, 60, 33, 35, 8, 9, 41, 44, 96, 4, 34, 53, 108, 112, 48, 130, 148, 75, 78, 66, 81, 166, 43, 178, 180, 95, 192, 98, 99, 84, 30, 222, 113, 228, 232, 7, 27, 50, 256, 262, 268, 69, 141, 272, 146, 153, 155, 312, 79

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

This sequence is a permutation of the positive integers.

LINKS

Lorenzo Sauras Altuzarra, Table of n, a(n) for n = 1..10000

MAPLE

lista := proc(n)

local k, m, x, L;

L := []:

for k from 1 to n do

m := iquo(k, 2^padic:-ordp(k, 2)*5^padic:-ordp(k, 5)):

if m > 1 then

x := numtheory:-order(10, m):

if not x in L then

L := [op(L), x]: fi: fi: od:

L: end:

lista(317);

PROG

(PARI) lista(nn) = my(list=List()); for (n=1, nn, my(x = znorder(Mod(10, n/2^valuation(n, 2)/5^valuation(n, 5)))); if (!vecsearch(vecsort(list), x), listput(list, x)); ); Vec(list); \\ Michel Marcus, Feb 18 2026

(Python)

from itertools import count, islice

from sympy import n_order, multiplicity

def A392345_gen(): # generator of terms

s = set()

for n in count(1):

if (a:=n_order(10, b) if (b:=(n>>(~n&n-1).bit_length())//5**multiplicity(5, n)) > 1 else 1) not in s:

yield a

s.add(a)

A392345_list = list(islice(A392345_gen(), 30)) # Chai Wah Wu, Feb 24 2026

CROSSREFS

Cf. A007732.