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A135564 Modulo 2 second differential integer sequence based on the Nørgård type form: second differential form as = a(n) - 2*a(n-1) + a(n-2). 1
0, 1, 3, -1, -2, -3, 4, 2, 1, 0, 1, 7, -7, -10, 2, 2, 1, -7, 1, 10, -1, -2, -6, -6, 14, 12, 3, -2, -12, 8, 0, -11, 1, -14, 8, 20, -8, -7, -9, -2, 11, -5, 1, 0, 4, 24, 0, -10, -20, -17, 2, -2, 9, -11, 5, 27, 10, 17, -20, -24, 8, 13, 11, -19, -12, 16, 15, 18, -22, -45, -12, 15, 28, -9, -1, 9, 2, 42, -7, -36, -13, -10, 16, 7, -6, -12, 1, 30, -4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

This sequence related to a Born-von Karman phonon model as well as the Nørgård infinite series; also related to my Ulam experiments.

The composer Per Nørgård's name is also written in the OEIS as Per Noergaard.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

Jørgen Mortensen, Construction by programming

FORMULA

p(i) = If[Mod[i, 2] == 0, p(i - 2) - (p(Floor[i/2]) - 2*([Abs[Floor[i/2] - 1]) + p(Abs[Floor[i/2] - 2])), p(i - 1) - ( p(Abs[Floor[i/2] - 2]) - 2*p(Abs[Floor[i/2] - 3]) + p(Abs[Floor[i/2] - 4]) )].

MATHEMATICA

p[0] = 0; p[1] = 1; p[2] = 3; p[3] = p[0] - 1; p[4] = p[3] - 1; p[i_]:= If[Mod[i, 2] == 0, p[i - 2] - (p[Floor[i/2]] - 2*p[ Abs[Floor[i/2] - 1]] + p[Abs[ Floor[i/2] - 2]]), p[i - 1] - (p[Abs[ Floor[i/2] - 2]] - 2*p[Abs[Floor[i/2] - 3]] + p[Abs[Floor[i/2] - 4]])]; b = Table[p[n], {n, 0, 100}]

CROSSREFS

Cf. A122581.

Sequence in context: A211948 A021766 A286357 * A110063 A260313 A050056

Adjacent sequences:  A135561 A135562 A135563 * A135565 A135566 A135567

KEYWORD

uned,sign

AUTHOR

Roger L. Bagula, Feb 23 2008

STATUS

approved

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Last modified November 12 19:25 EST 2019. Contains 329078 sequences. (Running on oeis4.)