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A238374 Row sums of triangle in A204026. 0
1, 2, 4, 6, 9, 12, 17, 22, 30, 38, 51, 64, 85, 106, 140, 174, 229, 284, 373, 462, 606, 750, 983, 1216, 1593, 1970, 2580, 3190, 4177, 5164, 6761, 8358, 10942, 13526, 17707, 21888, 28653, 35418, 46364, 57310, 75021, 92732, 121389, 150046, 196414, 242782 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..45.

Index entries for linear recurrences with constant coefficients, signature (1,1,-1,1,-1).

FORMULA

G.f.: (1+x)*(1+x^2)/((1-x^2-x^4)*(1-x)).

a(n) = a(n-1) + a(n-2) - a(n-3) + a(n-4) - a(n-5), a(0) = 1, a(1) = 2, a(2) = 4, a(3) = 6, a(4) = 9.

a(2*n) = A157728(n+5) = A000045(n+5) - 4.

a(2*n+1) = 2*A001911(n+1) = 2*A000045(n+4) - 4.

EXAMPLE

Triangle in A204026 begins:

1;.........................sum = 1

1, 1;......................sum = 2

1, 2, 1;...................sum = 4

1, 2, 2, 1;................sum = 6

1, 2, 3, 2, 1;.............sum = 9

1, 2, 3, 3, 2, 1;..........sum = 12

1, 2, 3, 5, 3, 2, 1;.......sum = 17

1, 2, 3, 5, 5, 3, 2, 1;....sum = 22

1, 2, 3, 5, 8, 5, 3, 2, 1;.sum = 30

MATHEMATICA

LinearRecurrence[{1, 1, -1, 1, -1}, {1, 2, 4, 6, 9}, 50] (* Harvey P. Dale, Feb 24 2018 *)

CROSSREFS

Cf. A000045, A001911, A157728, A204026

Sequence in context: A090631 A001365 A102379 * A133041 A079492 A267161

Adjacent sequences:  A238371 A238372 A238373 * A238375 A238376 A238377

KEYWORD

easy,nonn

AUTHOR

Philippe Deléham, Feb 25 2014

STATUS

approved

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Last modified June 23 05:11 EDT 2021. Contains 345395 sequences. (Running on oeis4.)