A055509 - OEIS

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A055509

Number of odd primes in sequence obtained in 3x+1 (or Collatz) problem starting at n.

0, 0, 2, 0, 1, 2, 5, 0, 5, 1, 4, 2, 2, 5, 3, 0, 3, 5, 6, 1, 0, 4, 3, 2, 6, 2, 24, 5, 5, 3, 23, 0, 6, 3, 2, 5, 6, 6, 10, 1, 24, 0, 7, 4, 3, 3, 22, 2, 6, 6, 5, 2, 2, 24, 23, 5, 7, 5, 10, 3, 4, 23, 19, 0, 6, 6, 8, 3, 2, 2, 21, 5, 24, 6, 1, 6, 5, 10, 10, 1, 4, 24, 23, 0, 0, 7, 8, 4, 9, 3, 19, 3, 2, 22, 19 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`a(A196871(n)) = 0. [Reinhard Zumkeller, Oct 08 2011]`
	LINKS	`Reinhard Zumkeller, Table of n, a(n) for n = 1..10000` `Eric Weisstein's World of Mathematics, Collatz Problem` `Wikipedia, Collatz conjecture` `Index entries for sequences related to 3x+1 (or Collatz) problem`
	FORMULA	`a(n) = A078350(n) - 1 for n > 1.`
	PROG	`(Haskell)` `a055509 n = sum $ map a010051 $ takeWhile (> 2) $ iterate a006370 n` `-- Reinhard Zumkeller, Oct 08 2011`
	CROSSREFS	`Cf. A055510.` `Cf. A006370, A010051.` `Sequence in context: A074704 A025247 A127767 * A006667 A112570 A127755` `Adjacent sequences: A055506 A055507 A055508 * A055510 A055511 A055512`
	KEYWORD	`nonn`
	AUTHOR	`G. L. Honaker, Jr. (honak3r(AT)gmail.com), Jun 30 2000`
	EXTENSIONS	`More terms from Larry Reeves (larryr(AT)acm.org), Aug 09 2001`

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Last modified February 17 13:28 EST 2012. Contains 206031 sequences.