login
A265546
a(n) = smallest base-4 palindrome m >= n such that every base-4 digit of n is <= the corresponding base-4 digit of m; m is written in base 10.
1
0, 1, 2, 3, 5, 5, 10, 15, 10, 10, 10, 15, 15, 15, 15, 15, 17, 17, 34, 51, 21, 21, 38, 55, 25, 25, 42, 59, 29, 29, 46, 63, 34, 34, 34, 51, 38, 38, 38, 55, 42, 42, 42, 59, 46, 46, 46, 63, 51, 51, 51, 51, 55, 55, 55, 55, 59, 59, 59, 59, 63, 63, 63, 63, 65, 65, 130, 195, 85, 85, 150, 215, 105, 105, 170, 235, 125, 125, 190
OFFSET
0,3
LINKS
PROG
(PARI) isok(m, dn) = {my(dm = digits(m, 4)); if ((Vecrev(dm) == dm) && (#dm == #dn), for (i=1, #dn, if (dn[i] > dm[i], return (0))); return(1); ); }
a(n) = {my(dn = digits(n, 4), m = n); while (!isok(m, dn), m++); m; } \\ Michel Marcus, Apr 07 2021
CROSSREFS
Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.
Sequence in context: A140312 A088887 A368085 * A066911 A326229 A326187
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Dec 10 2015
STATUS
approved