A050431 Length of longest palindromic subword of (n base 3).

1, 1, 1, 2, 1, 1, 1, 2, 2, 3, 1, 2, 3, 2, 1, 3, 2, 2, 1, 3, 1, 2, 3, 2, 2, 3, 3, 4, 2, 3, 3, 3, 3, 1, 2, 2, 3, 2, 3, 4, 3, 2, 3, 2, 2, 1, 3, 3, 3, 3, 2, 4, 3, 3, 2, 4, 3, 2, 1, 3, 3, 3, 2, 3, 1, 2, 3, 4, 3, 3, 3, 2, 2, 3, 2, 2, 3, 3, 3, 4, 4, 5, 3, 4, 4, 4, 3, 2, 2, 3

Offset

1,4

Links

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

Formula

a(n) <= min(a(3*n), a(3*n+1), a(3*n+2)). [Reinhard Zumkeller, Jul 31 2011]

Maple

LPS:= proc(L) local nL, n, i;
  nL:= nops(L);
  for n from nL to 1 by -1 do
    for i from 1 to nL-n+1 do
      if L[i..i+n-1] = ListTools:-Reverse(L[i..i+n-1]) then return n fi
  od od:
end proc:
seq(LPS(convert(n, base, 3)), n=1..100); # Robert Israel, Dec 17 2020

Crossrefs

Cf. A050430, A050432, A050433.

Sequence in context: A264990 A277315 A277326 * A051574 A029386 A277325

Adjacent sequences: A050428 A050429 A050430 * A050432 A050433 A050434

Keyword

nonn,base

Author

Clark Kimberling

Status

approved