3-, 4- and 5-letter palindromic sequences
(P3, P4, P5)--letter patterns 121, 1221 and 12321.
ROSS GOES AND RETURNS MIXED WITH A PALINDROMIC SEQUENCE
Middle row of typewriter keyboard (ASDFGHJKL) ASH FALLS, HALF FLASH (The Scoundrel's Dictionary--note also the palindromic sequence
ALFFLA), HALF GLASS, FLAG FALLS, SHAG ASS (be swift--bt)
A second palindromic sequence
(1221 ) is converted into a tautonymic sequence (1212 or 2121).
MABABABABA with its uninterrupted quadruple bigram BA; and CHANCACACCACCA with its A/C run of 10 letters which include the 7-letter palindromic sequence
And here's another possible record-breaker from Susan: "The 13-letter palindromic sequence
in PAHALAWALAHAPITIYI (a populated place in Sri Lanka) must surely be a contender for the longest palindromic sequence
forming part of a word.
Repetitive extragenic palindromic sequences
consist of highly conserved inverted repeat sequences approximately 35 bp long (Stern et al.