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A190036 Number of nondecreasing arrangements of n+2 numbers in 0..4 with the last equal to 4 and each after the second equal to the sum of one or two of the preceding three. 1
7, 12, 18, 27, 39, 53, 69, 87, 107, 129, 153, 179, 207, 237, 269, 303, 339, 377, 417, 459, 503, 549, 597, 647, 699, 753, 809, 867, 927, 989, 1053, 1119, 1187, 1257, 1329, 1403, 1479, 1557, 1637, 1719, 1803, 1889, 1977, 2067, 2159, 2253, 2349, 2447, 2547, 2649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A190041.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = n^2 + 3*n - 1 for n>3.

Conjectures from Colin Barker, May 04 2018: (Start)

G.f.: x*(7 - 9*x + 3*x^2 + 2*x^3 - x^5) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>4.

(End)

EXAMPLE

Some solutions for n=3:

  2  1  1  3  1  2  0  1  0  1  1  2  0  1  1  4

  2  1  1  4  4  2  2  2  2  3  2  2  4  2  3  4

  4  2  2  4  4  2  2  2  2  3  2  2  4  3  4  4

  4  2  3  4  4  4  2  2  4  4  4  2  4  4  4  4

  4  4  4  4  4  4  4  4  4  4  4  4  4  4  4  4

CROSSREFS

Cf. A190041.

Sequence in context: A247159 A022953 A030714 * A061141 A256381 A272975

Adjacent sequences:  A190033 A190034 A190035 * A190037 A190038 A190039

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 04 2011

STATUS

approved

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Last modified October 19 22:05 EDT 2021. Contains 348095 sequences. (Running on oeis4.)