0,2

The analog of A023109 in base 2.

Chai Wah Wu, Table of n, a(n) for n = 0..100

11 is the smallest integer which requires two steps to reach a base 2 palindrome (cf. A066057), so a(2) = 11; written in base 10: 11 -> 11 + 13 = 24 -> 24 + 3 = 27; written in base 2: 1011 -> 1011 + 1101 = 11000 -> 11000 + 11 = 11011.

Table[ SelectFirst[Range[0, 20000], (np = #; i = 0;

While[ np != IntegerReverse[np, 2] && i <= n,

np = np + IntegerReverse[np, 2]; i++];

i == n ) &] , {n, 0, 44}] (* Robert Price, Oct 16 2019 *)

(ARIBAS) (* For function b2reverse see A066057. *) function a066058(mx: integer); var k, m, n, rev, steps: integer; begin for k := 0 to mx do n := 0; steps := 0; m := n; rev := b2reverse(m); while not(steps = k and m = rev) do inc(n); m := n; rev := b2reverse(m); steps := 0; while steps < k and m <> rev do m := m + rev; rev := b2reverse(m); inc(steps); end; end; write(n, ", "); end; end; a066058(45);

(Python)

def A066058(n):

if n > 0:

k = 0

while True:

m = k

for i in range(n):

s1 = format(m, 'b')

s2 = s1[::-1]

if s1 == s2:

break

m += int(s2, 2)

else:

s1 = format(m, 'b')

if s1 == s1[::-1]:

return k

k += 1

else:

return 0 # Chai Wah Wu, Jan 06 2015

Cf. A066057, A023109, A062128, A062130, A033865, A006995, A057148.

Sequence in context: A050620 A027253 A241712 * A153440 A373542 A392570

Adjacent sequences: A066055 A066056 A066057 * A066059 A066060 A066061

base,nonn

Klaus Brockhaus, Dec 04 2001

approved