A088593 a(0)=18; a(n+1) = largest odd factor of 3*a(n)+1; stop when a(n)=1.

18, 55, 83, 125, 47, 71, 107, 161, 121, 91, 137, 103, 155, 233, 175, 263, 395, 593, 445, 167, 251, 377, 283, 425, 319, 479, 719, 1079, 1619, 2429, 911, 1367, 2051, 3077, 577, 433, 325, 61, 23, 35, 53, 5, 1

Offset: 0

Author

Mitch Cervinka (puritan(AT)planetkc.com), Nov 20 2003

Keywords

• easy
• nonn
• fini
• full

Comments

Similar to a Collatz sequence.

Examples

			a(4)=47 because (a(3)*3+1)/2^3 = 47.
		

Crossrefs

Cf. A000265.

Programs

PARI

f(n) = n >> valuation(n, 2); \\ A000265
lista(nn) = my(list=List(), x = 18, i=0); while (1, listput(list, x); x = f(3*x+1); i++; if (i>100, break)); Vec(list); \\ Michel Marcus, Aug 23 2022

Formula

a(n+1) = A000265(3*a(n)+1). - Michel Marcus, Aug 23 2022

Extensions

Edited by Don Reble, Nov 08 2005

Corrected by Doug Unger, Aug 26 2022