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A228212 Number of second differences of arrays of length n + 2 of numbers in 0..2. 2
9, 49, 199, 665, 2059, 6305, 19171, 58025, 175099, 527345, 1586131, 4766585, 14316139, 42981185, 129009091, 387158345, 1161737179, 3485735825, 10458256051, 31376865305, 94134790219, 282412759265, 847255055011, 2541798719465 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 5*a(n-1) -6*a(n-2) = A001047(n+2) for n>5.
Conjectures from Colin Barker, Sep 09 2018: (Start)
G.f.: x*(9 + 4*x + 8*x^2 - 36*x^3 - 72*x^4) / ((1 - 2*x)*(1 - 3*x)).
a(n) = 3^(2+n) - 2^(2+n) for n>3.
(End)
EXAMPLE
Some solutions for n=4:
..3....3...-4....0....1....0...-3...-1...-2....4....0...-4....0....0....3....2
.-1...-2....3....3...-1...-2....2....0....4...-4....0....3...-2...-1....0...-1
.-1...-1....0...-3....0....1...-2....1...-2....4....1....0....0....0...-3....0
..2....1...-2....2....0....1....0...-3...-2...-2...-3...-3....3...-1....3....1
CROSSREFS
Column 2 of A228218.
Sequence in context: A082608 A058031 A359726 * A027608 A354657 A003297
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 16 2013
STATUS
approved

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Last modified March 1 08:46 EST 2024. Contains 370430 sequences. (Running on oeis4.)