A242397 -id:A242397 - cp's OEIS frontend

A258165 Odd non-Brazilian numbers > 1.

3, 5, 9, 11, 17, 19, 23, 25, 29, 37, 41, 47, 49, 53, 59, 61, 67, 71, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 223, 227, 229, 233, 239, 251, 257, 263, 269, 271, 277, 281, 283, 289, 293, 311, 313, 317, 331, 337

Offset: 1

Daniel Lignon and Robert G. Wilson v, May 22 2015

nonn

Complement of A257521 in A144396 (odd numbers > 1).
The terms are only odd primes or squares of odd primes.
Most odd primes are present except those in A085104.
All terms which are not primes are squares of odd primes except 121 = 11^2.

			11 is present because there is no base b < 11 - 1 = 10 such that the representation of 11 in base b is a repdigit (all digits are equal). In fact, we have: 11 = 1011_2 = 102_3 = 23_4 = 21_5 = 15_6 = 14_7 = 13_8 = 12_9, and none of these representations are repdigits. - _Bernard Schott_, Jun 21 2017

Vincenzo Librandi, Table of n, a(n) for n = 1..1150

Cf. A085104, A125134, A190300, A220570, A220571, A220627, A242397, A253260, A253261, A257521.

fQ[n_] := Block[{b = 2}, While[b < n - 1 && Length@ Union@ IntegerDigits[n, b] > 1, b++]; b+1 == n]; Select[1 + 2 Range@ 170, fQ]

forstep(n=3, 300, 2, c=1; for(b=2, n-2, d=digits(n, b); if(vecmin(d)==vecmax(d), c=0;  break));if(c,print1(n,", "))) \\ Derek Orr, May 27 2015

from sympy.ntheory.factor_ import digits
l=[]
for n in range(3, 301, 2):
    c=1
    for b in range(2, n - 1):
        d=digits(n, b)[1:]
        if max(d)==min(d):
            c=0
            break
    if c: l.append(n)
print(l) # Indranil Ghosh, Jun 22 2017, after PARI program

A371812 Number of different ways A329383(n) is Brazilian.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 9, 11, 14, 15, 16, 17, 19, 23, 29, 31, 35, 39, 41, 44, 47, 49, 52, 59, 63, 71, 79, 83, 89, 95, 99, 107, 111, 119, 127, 143, 159, 167, 179, 190, 191, 199, 215, 223, 239, 251, 255, 287, 299, 319, 335, 359, 383, 399, 431, 447, 479, 503

Offset: 1

Daniel Mondot, Apr 06 2024

Or number of bases from 2 to n-2 in which the highly Brazilian number A329383(n) is a repdigit number.

Note that from a(26) to a(75) except for a(31) and a(42), a(n) = 4k-1 for some k.

			A329383(2) = 7 is Brazilian in only 1 base below 6 (base 2), so a(2) = 1.
A329383(3) = 15 is Brazilian in 2 bases below 14 (bases 2, 4), so a(3) = 2.

Daniel Mondot, Table of n, a(n) for n = 1..91

Cf. A329383, A284758, A242397.

#include 
FILE *fi;
unsigned int cnt, d, line;
long unsigned base, k, ln;
void main()
{
    fi = fopen("b329383.txt", "r");
    for(;;)
    {
        if (fscanf(fi, "%u %lu", &line, &ln) < 2) break;
        for (cnt=0, base=2; base

cp's OEIS Frontend

A258165 Odd non-Brazilian numbers > 1.

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