id:A075685 - OEIS Search Results

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Reverse and Add! carried out in base 4; number of steps needed to reach a palindrome, or -1 if no palindrome is ever reached.

+0
5

0, 0, 0, 0, 1, 0, 1, 2, 1, 1, 0, 1, 1, 2, 1, 0, 1, 0, 1, 2, 1, 0, 1, 2, 2, 0, 3, 2, 4, 0, 4, 3, 1, 1, 0, 1, 1, 1, 0, 4, 2, 3, 0, 2, 3, 4, 0, 4, 1, 2, 1, 0, 1, 2, 4, 0, 3, 2, 2, 0, 4, 3, 4, 0, 1, 0, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 2, 1, 0, 1, 3, 1, 1, 1, 2, 2, 3, 3, 2, 1, 1, 1, 3, 1, 1, 1, 2, 2 (list; graph; listen)

	OFFSET	`0,8`
	COMMENT	`Base 4 analogue of A033665 (base 10) and A066057 (base 2). For values of n such that presumably a(n) = -1 see A075420.`
	LINKS	`Index entries for sequences related to Reverse and Add!`
	EXAMPLE	`26 (decimal) = 122 -> 122 + 221 = 1003 -> 1003 + 3001 = 10010 -> 10010 + 01001 = 11011 (palindrome) = 325 (decimal) requires 3 steps, so a(26) = 3.`
	PROGRAM	`(ARIBAS) m := 105; stop := 1000; for n := 0 to m do c := 0; k := n; v := -1; while c < stop do a := k; rev := 0; while a > 0 do rev := 4*rev + (a mod 4); a := a div 4; end; if k = rev then v := c; c := stop; else inc(c); k := k + rev; end; end; write(v, " "); end; .`
	CROSSREFS	`Cf. A014192, A033665, A066057, A075420.` `Sequence in context: A060763 A131576 A100073 this_sequence A037906 A120936 A101675` `Adjacent sequences: A075682 A075683 A075684 this_sequence A075686 A075687 A075688`
	KEYWORD	`base,nonn`
	AUTHOR	`Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Sep 24 2002`

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Last modified November 22 20:51 EST 2009. Contains 167312 sequences.

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