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A085349 Ratio-determined insertion sequence I(0.26688) (see the link below). 2
1, 4, 15, 71, 269, 1274, 4827, 22861, 86617, 410224, 1554279, 7361171, 27890405, 132090854, 500473011, 2370274201, 8980623793, 42532844764, 161150755263, 763220931551, 2891732970941, 13695443923154, 51890042721675 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
This is one of the "twin" ratio-determined insertion sequences (RDIS) that are "children" in the next generation below the "parent" sequences I(0.25024) (A004253) and I(0.26816) (A001353) in the recurrence tree of RDIS sequences. The RDIS twin of this sequence is A085348. See the link for an explanation of RDIS twin. See A082630 or A082981 for other recent examples of RDIS sequences.
LINKS
John W. Layman, Ratio-Determined Insertion Sequences and the Tree of their Recurrence Types, June 2003 [local copy, corrected]
John W. Layman, Sequences Generated by Age-Determined Insertion Trees, Jan 2006 [Local copy]
FORMULA
It appears that a(n)=18a(n-2)-a(n-4).
Apparently a(n)a(n+3) = 11 + a(n+1)a(n+2). - Ralf Stephan, May 29 2004
MATHEMATICA
LinearRecurrence[{0, 18, 0, -1}, {1, 4, 15, 71}, 30] (* Harvey P. Dale, Mar 04 2013 *)
CROSSREFS
Sequence in context: A356407 A366034 A027316 * A185133 A278640 A026992
KEYWORD
nonn
AUTHOR
John W. Layman, Jun 24 2003
STATUS
approved

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Last modified May 29 00:29 EDT 2024. Contains 372921 sequences. (Running on oeis4.)