A272670 Numbers whose binary expansion is not palindromic but which when reversed and leading zeros omitted, does form a palindrome.

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 32, 34, 36, 40, 42, 48, 54, 56, 60, 62, 64, 66, 68, 72, 80, 84, 90, 96, 102, 108, 112, 120, 124, 126, 128, 130, 132, 136, 144, 146, 160, 168, 170, 180, 186, 192, 198, 204, 214, 216, 224, 238, 240, 248, 252, 254

Offset

1,1

Comments

Decimal interpretation of A273245. Twice A057890.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Maple

isPal := proc(L::list)
    local i;
    for i from 1 to nops(L)/2 do
        if op(i, L) <> op(-i, L) then
            return false;
        end if;
    end do:
    true ;
end proc:
isA272670 := proc(n)
    local bdgs ;
    bdgs := convert(n, base, 2) ;
    if isPal(bdgs) then
        return false;
    else
        A000265(n) ;
        bdgs := convert(%, base, 2) ;
        isPal(bdgs) ;
    end if;
end proc:
for n from 1 to 500 do
    if isA272670(n) then
        printf("%d, ", n) ;
    end if;
end do: # R. J. Mathar, May 20 2016

Prog

(Python)
A272670_list = [n for n in range(1, 10**4) if bin(n)[2:] != bin(n)[:1:-1] and bin(n)[2:].rstrip('0') == bin(n)[:1:-1].lstrip('0')] # Chai Wah Wu, May 21 2016

Crossrefs

Cf. A006995, A057890, A273245, A273329, subsequence of A154809.

Sequence in context: A029741 A240171 A221284 * A234521 A085125 A251237

Adjacent sequences: A272667 A272668 A272669 * A272671 A272672 A272673

Keyword

nonn,base,easy

Author

N. J. A. Sloane, May 19 2016

Status

approved