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A122437 Allowable values of the "dropping time" of the Collatz (3x+1) iteration. +0
4
1, 3, 6, 8, 11, 13, 16, 19, 21, 24, 26, 29, 32, 34, 37, 39, 42, 44, 47, 50, 52, 55, 57, 60, 63, 65, 68, 70, 73, 75, 78, 81, 83, 86, 88, 91, 94, 96, 99, 101, 104, 106, 109, 112, 114, 117, 119, 122, 125, 127, 130, 132, 135, 138, 140, 143, 145, 148, 150, 153, 156, 158, 161 (list; graph; listen)
OFFSET

1,2

COMMENT

Only these numbers appear in A060445, which tabulates the "dropping time" of odd numbers. Note that all even numbers have a "dropping time" of 1.

FORMULA

a(1)=1, a(n+1)=a(n)+A022921(n-1)+1

a(n+1)=floor(1+n+n*log(3)/log(2)) - T. D. Noe (noe(AT)sspectra.com), Sep 08 2006

MATHEMATICA

Floor[1+Range[0, 100]*(1+Log[2, 3])] - T. D. Noe (noe(AT)sspectra.com), Sep 08 2006

CROSSREFS

Cf. A022921 (number of 2^m between 3^n and 3^(n+1)), A122442 (least k having dropping time a(n)).

Sequence in context: A047219 A138373 A139477 this_sequence A090848 A004957 A026352

Adjacent sequences: A122434 A122435 A122436 this_sequence A122438 A122439 A122440

KEYWORD

nice,nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Sep 06 2006

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.


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