A068642 Index of the smallest n-digit palindromic triangular number, or 0 if no such number exists.

1, 10, 18, 77, 173, 1111, 1593, 8382, 18906, 50281, 167053, 0, 1620621, 6307938, 15126258, 50008881, 149142458, 846122222, 2480116437, 5513600773, 14667896198, 49786655918, 246644446642, 529670494286, 2466444446642

Offset

1,2

Links

Table of n, a(n) for n=1..25.

P. De Geest, Exhaustive list of Palindromic Triangulars

Example

a(4) = 77 as 77*78/2 = 3003 is the smallest 4-digit palindromic triangular number.
a(12) = 0 as no 12-digit palindromic triangular number exists.

Crossrefs

Cf. A068641, A068643, A068644, A000217, A003098, A008509, A008510, A054263.

Sequence in context: A266708 A186235 A241053 * A198309 A167342 A288781

Adjacent sequences: A068639 A068640 A068641 * A068643 A068644 A068645

Keyword

base,nonn,changed

Author

Amarnath Murthy, Feb 28 2002

Extensions

Edited by Patrick De Geest, Mar 24 2002

Status

approved