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A050425 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 1. 4
2, 6, 10, 11, 13, 14, 18, 19, 23, 25, 29, 30, 34, 35, 37, 41, 42, 43, 47, 49, 53, 54, 55, 59, 61, 62, 66, 67, 69, 77, 81, 83, 89, 90, 91, 95, 97, 101, 102, 103, 109, 111, 115, 123, 125, 126, 130, 131, 133, 137, 145, 146, 147, 149, 157, 161, 163, 169, 170, 171 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..60.

EXAMPLE

(13 base 2) = 1101 -> 111.

PROG

(Python)

def ok(n):

    b = bin(n)[2:]

    if b == b[::-1]: return False

    for skip in range(len(b)):

        newb = b[:skip] + b[skip+1:]

        if len(newb) > 0 and newb[0] == '1' and newb == newb[::-1]:

            return True

    return False

print(list(filter(ok, range(172)))) # Michael S. Branicky, Aug 24 2021

CROSSREFS

Subsequence of A050420 (possibly beginning with digit 0).

Cf. A050426, A050427, A050428, A050429.

Sequence in context: A054645 A337645 A225271 * A030405 A125241 A116043

Adjacent sequences:  A050422 A050423 A050424 * A050426 A050427 A050428

KEYWORD

nonn,base

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified October 20 05:54 EDT 2021. Contains 348099 sequences. (Running on oeis4.)