A087970 Maximal term in Collatz-iteration started at 2^n+1.

2, 16, 16, 52, 52, 100, 196, 9232, 9232, 1540, 3076, 9232, 12292, 24580, 49156, 98308, 196612, 393220, 786436, 1572868, 3145732, 6291460, 12582916, 25165828, 50331652, 100663300, 201326596, 402653188, 805306372, 1610612740, 3221225476, 6442450948, 12884901892

Offset

0,1

Links

Amiram Eldar, Table of n, a(n) for n = 0..1000

Formula

a(n) = A025586(2^n+1).

Conjectures from Chai Wah Wu, Sep 18 2025: (Start)

a(n) = 3*a(n-1) - 2*a(n-2) for n > 13.

G.f.: (6168*x^13 - 9252*x^12 + 3084*x^11 + 16920*x^10 - 7692*x^9 - 18072*x^8 + 8844*x^7 + 48*x^5 - 72*x^4 + 36*x^3 - 28*x^2 + 10*x + 2)/((x - 1)*(2*x - 1)). (End)

Crossrefs

Cf. A000051, A025586, A087701, A087972.

Sequence in context: A066773 A138761 A380138 * A247634 A261617 A075376

Adjacent sequences: A087967 A087968 A087969 * A087971 A087972 A087973

Keyword

nonn

Author

Labos Elemer, Sep 24 2003

Extensions

Offset changed to 0, a(0) prepended and more terms added by Amiram Eldar, Jun 04 2024

Status

approved