A050429 Numbers for which in base 2 the least number of digits that can be removed to leave a base 2 palindromic number (beginning with 1) is 5.

32, 96, 160, 176, 208, 224, 288, 304, 312, 368, 400, 456, 464, 480, 544, 560, 568, 572, 592, 600, 604, 632, 656, 672, 688, 696, 752, 784, 840, 848, 864, 880, 904, 932, 936, 944, 964, 968, 976, 992, 1056, 1072, 1080, 1084, 1086, 1104, 1112, 1116, 1118, 1128

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Prog

(Python)
from itertools import combinations
def ok(n):
    b = bin(n)[2:]
    for digs_to_remove in range(6):
        for skip in combinations(range(len(b)), digs_to_remove):
            newb = "".join(b[i] for i in range(len(b)) if i not in skip)
            if len(newb) > 0 and newb[0] == '1' and newb == newb[::-1]:
                return (digs_to_remove == 5)
    return False
print(list(filter(ok, range(1129)))) # Michael S. Branicky, Aug 15 2021

Crossrefs

Sequence in context: A208635 A259715 A195088 * A362841 A044219 A044600

Adjacent sequences: A050426 A050427 A050428 * A050430 A050431 A050432

Keyword

nonn,base

Author

Clark Kimberling

Extensions

Data corrected and extended by Sean A. Irvine, Aug 15 2021

Status

approved