Determine the minimum value of a hexagonal number H(p) = 2p² - p, such that each of p and H(p) is a base ten palindrome.

*** p must have more than one digit, so trivial solutions like p=0,1 are not valid.

DEFDBL A-Z
FOR p = 11 TO 999999
  p$ = LTRIM$(STR$(p))
  good = 1
  FOR i = 1 TO LEN(p$) / 2
    IF MID$(p$, i, 1) <> MID$(p$, LEN(p$) + 1 - i, 1) THEN good = 0: EXIT FOR
  NEXT
  IF good THEN
    h = 2 * p * p - p
    h$ = LTRIM$(STR$(h))
    FOR i = 1 TO LEN(h$) / 2
      IF MID$(h$, i, 1) <> MID$(h$, LEN(h$) + 1 - i, 1) THEN good = 0: EXIT FOR
    NEXT
    IF good THEN PRINT p, h
  END IF
NEXT p

finds only

 p            H(p)
55            5995
797           1269621

Posted by Charlie on 2013-11-26 19:42:25