A048343 Total number of distinct palindromes of form 'n-digit number' x 'n-digit number_reversed' (n-digit number not palindromic).

0, 1, 3, 10, 19, 44, 86, 171, 308, 551, 920

Offset

1,3

Links

Table of n, a(n) for n=1..11.

P. De Geest, Palindromic Products of Non Palindromic Integers and their Reversals

Example

E.g., 3 solutions for 3-digit numbers: 102 * 201 = 20502; 112 * 211 = 23632; 122 * 221 = 26962.

Prog

(Python)
def A048343(n):
....y, plist = 0, []
....for i in range(10**(n-1), 10**n):
........s1 = str(i)
........s2 = s1[::-1]
........if s1 != s2:
............p = i*int(s2)
............if not p in plist:
................sp = str(p)
................if sp == sp[::-1]:
....................plist.append(p)
....................y += 1
....return y # Chai Wah Wu, Sep 05 2014

Crossrefs

Cf. A048344.

Sequence in context: A160002 A294421 A027177 * A056789 A174476 A098645

Adjacent sequences: A048340 A048341 A048342 * A048344 A048345 A048346

Keyword

nonn,base,more

Author

Patrick De Geest, Feb 15 1999

Extensions

More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 18 2006

Offset changed and two terms added by Lars Blomberg, Nov 25 2011

Status

approved