OFFSET
1,3
COMMENTS
The numbers 2*m, 4*m and 8*m are also terms of the sequence for m=a(122). - Dimiter Skordev, Mar 29 2020
LINKS
Dimiter Skordev, Table of n, a(n) for n = 1..122 (terms < 10^15, terms 1..36 from Erich Friedman, 37..111 from Dimiter Skordev, 112..120 from Giovanni Resta)
Dimiter Skordev, Pascal program
Dimiter Skordev, Python script
EXAMPLE
30 = 11110_2; 11110_3 = 120 = 4*30.
MATHEMATICA
{0} ~Join~ Select[Range[10^5], Mod[ FromDigits[ IntegerDigits[#, 2], 3], #] == 0 &] (* Giovanni Resta, Dec 10 2019 *)
PROG
(Magma) [0] cat [k:k in [1..100000]|Seqint(Intseq(Seqint(Intseq(k, 2))), 3) mod k eq 0]; // Marius A. Burtea, Dec 29 2019
(PARI) isok(m) = (m==0) || fromdigits(digits(m, 2), 3) % m == 0; \\ Michel Marcus, Feb 15 2020
(Python)
def BaseUp(n, b):
up, b1 = 0, 1
while n > 0:
up, b1, n = up+(n%b)*b1, b1*(b+1), n//b
return up
n, k = 1, 0
print(1, 0)
while n < 35:
n, k = n+1, k+1
while BaseUp(k, 2)%k != 0:
k = k+1
print(n, k) # A.H.M. Smeets, Mar 31 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Erich Friedman, Jul 21 2001
STATUS
approved