A077402 - OEIS

This site is supported by donations to The OEIS Foundation.

A077402

Reverse and Add! carried out in base 3; number of steps needed to reach a palindrome, or -1 if no palindrome is ever reached.

0, 0, 0, 1, 0, 2, 1, 2, 0, 1, 0, 2, 1, 0, 2, 3, 0, 4, 1, 2, 0, 1, 2, 0, 3, 4, 0, 1, 0, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 0, 2, 3, 3, 2, 1, 1, 2, 3, 3, 2, 3, 0, 18, 1, 2, 0, 1, 2, 4, 1, 2, 2, 1, 2, 4, 1, 2, 0, 3, 2, 4, 1, 2, 2, 3, 2, 4, 17, 18, 0, 1, 0, 2, 1, 1, 2, 1, 1, 3, 1, 0, 2, 1, 1, 16, 1, 1, 2, 2, 0, 2, 4, -1, 16, 3, 15, 2, 1, 1, 2, 1, 0, 3, 3, 3, 2, 1, 1, 16, 1 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,6`
	COMMENTS	`Base 3 analogue of A066057 (base 2), A075685 (base 4) and A033665 (base 10). a(103) = -1 is a conjecture (cf. A066450, A077408). For values of n such that presumably a(n) = -1 see A077404.`
	LINKS	`Index entries for sequences related to Reverse and Add!`
	EXAMPLE	`17 (decimal) = 122 -> 122 + 221 = 1120 -> 1120 + 211 = 2101 -> 2101 + 1012 = 10120 -> 10120 + 2101 = 12221 (palindrome) = 160 (decimal) requires 4 steps, so a(17) = 4.`
	PROG	`(ARIBAS) m := 120; stop := 1000; for n := 0 to m do v := -1; c := 0; k := n; while c < stop do d := k; rev := 0; while d > 0 do rev := 3*rev + (d mod 3); d := d div 3; end; if k = rev then v := c; c := stop; else inc(c); k := k + rev; end; end; write(v, ", "); end;`
	CROSSREFS	`Cf. A014190, A066450, A033665, A066057, A075685, A077404, A077405.` `Sequence in context: A139351 A125925 A036578 * A137853 A094114 A104607` `Adjacent sequences: A077399 A077400 A077401 * A077403 A077404 A077405`
	KEYWORD	`base,sign`
	AUTHOR	`Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 05 2002`

Content is available under The OEIS End-User License Agreement .

Last modified February 15 07:42 EST 2012. Contains 205717 sequences.