A124334 Nonpalindromes in base 10 that are palindromes in base 2.

15, 17, 21, 27, 31, 45, 51, 63, 65, 73, 85, 93, 107, 119, 127, 129, 153, 165, 189, 195, 219, 231, 255, 257, 273, 297, 325, 341, 365, 381, 387, 403, 427, 443, 455, 471, 495, 511, 513, 561, 633, 645, 693, 765, 771, 819, 843, 891, 903, 951, 975

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

17(10) = 10001(2), a palindrome.

Maple

N:= 10000: # to get the first N entries
count:= 0:
for d from 1 while count < N do
   d1:= ceil(d/2); d2:= d - d1;
   for x from 2^(d1-1) to 2^d1 - 1 while count < N do
      if d::even then x1:= x else x1 := floor(x/2) fi;
      L:= convert(x1, base, 2);
      y:= 2^(d2)*x + add(L[j]*2^(d2-j), j=1..d2);
      L10:= convert(y, base, 10);
      if ListTools[Reverse](L10) = L10 then next fi;
      count:= count+1;
      A[count]:= y;
   od
od:
seq(A[n], n=1..N);
# Robert Israel, Apr 20 2014

Mathematica

Select[Range[1000], Reverse[IntegerDigits[ # ]] != IntegerDigits[ # ] && Reverse[IntegerDigits[ #, 2]] == IntegerDigits[ #, 2] &]

Crossrefs

Cf. A007632 = numbers that are palindromic in bases 2 and 10.

Sequence in context: A074748 A183981 A155111 * A002155 A290749 A374005

Adjacent sequences: A124331 A124332 A124333 * A124335 A124336 A124337

Keyword

base,nonn

Author

Tanya Khovanova, Dec 26 2006

Status

approved