A118129 Numbers k such that the sum of the first k odd composites is palindromic in base 3.

6, 14, 20, 424, 1042, 8290, 20802, 21644, 440512, 548008, 749171, 4366390, 5378548, 9850174, 17930596, 36158854, 130427194, 407305710, 3077094752, 93416875260

Offset: 1

Author

Ryan Propper, May 12 2006

Keywords

• nonn
• base
• hard
• more

Comments

No more terms through 10^9.

Any subsequent terms are > 10^11. - Lucas A. Brown, Aug 12 2024

Examples

			The sum of the first 14 odd composites, when written in base 3, is the palindrome 201102, so 14 is in the sequence.
		

Links

• Lucas A. Brown, Python program.

Crossrefs

Cf. A058848 (palindromic in base 10).

Extensions

a(19)-a(20) from Lucas A. Brown, Aug 12 2024