login
A368841
Nonnegative integers whose binary expansions (without leading zeros) have no three equally spaced equal digits.
2
0, 1, 2, 3, 4, 5, 6, 9, 10, 11, 12, 13, 18, 19, 20, 22, 25, 26, 27, 36, 37, 38, 41, 44, 45, 50, 51, 52, 54, 76, 82, 83, 90, 100, 101, 102, 108, 153, 165, 204
OFFSET
1,3
COMMENTS
Also numbers k such that A368842(k) = 0.
Also numbers k such that A368857(k) < 3.
This sequence is finite by Van der Waerden's theorem.
PROG
(PARI) is(n, base = 2) = { my (d = digits(n, base)); for (i = 1, #d-2, forstep (j = i+2, #d, 2, if (d[i]==d[j] && d[i]==d[(i+j)/2], return (0); ); ); ); return (1); }
CROSSREFS
KEYWORD
nonn,base,easy,fini,full
AUTHOR
Rémy Sigrist, Jan 07 2024
STATUS
approved