A319387 Smallest palindrome p such that n-p is again a palindrome, or n if no such p exists.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 21, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 32, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 43, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 54, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 65, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 76, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 87, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 98, 0

Offset

0,14

Comments

a(n) = n if and only if A262087(n) = 0.

Links

Robert Israel, Table of n, a(n) for n = 0..10000

Example

a(11) = 0 because 11 = 11 + 0, so 0 is the smallest palindrome in any partitioning of 11 as a sum of two palindromes.
a(21) = 21 because 21 cannot be written as a sum of two palindromes.

Maple

isP := k -> StringTools[IsPalindrome](convert(k, string)):
a := NULL:
for n from 0 to 99 do
   an := n:
   for k from 0 to n/2 do
      if isP(k) and isP(n-k) then an := min(an, k) end if
   end do:
   a := a, an
end do:
a;

Crossrefs

Cf. A002113, A035137, A260254, A262087.

Sequence in context: A114800 A079170 A330927 * A076105 A094280 A082323

Adjacent sequences: A319384 A319385 A319386 * A319388 A319389 A319390

Keyword

nonn,base,look

Author

Markus Sigg, Sep 18 2018

Status

approved