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

Author

N. J. A. Sloane, May 19 2016

Keywords

• nonn
• base
• easy

Comments

Decimal interpretation of A273245. Twice A057890.

Links

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

Crossrefs

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

Programs

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

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