A054540 -id:A054540 - cp's OEIS frontend

A060233 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to six complementary pairs of ratios which generate simple musical tones (scale steps): 8/7 and 7/4, 6/5 and 5/3, 16/13 and 13/8, 5/4 and 8/5, 4/3 and 3/2 and 11/8 and 16/11.

1, 2, 3, 4, 6, 7, 9, 10, 15, 19, 22, 24, 26, 31, 37, 41, 46, 50, 53, 72, 84, 87, 130, 137, 140, 171, 183, 217, 224, 270, 494, 764, 851, 1038, 1282, 1308, 1578, 2190, 2684, 3395, 4843, 5004, 5585, 6079, 8269, 14124, 14618, 17302, 20203, 22887, 31737

Offset: 1

Mark William Rankin (MarkRankin95511(AT)Yahoo.com), Apr 14 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to over 31737. The numerical value of each term represents a musical scale based on an equal division of the octave. 19, for example, signifies the scale which is formed by dividing the octave into 19 equal parts.

			6 = 4 + the previous term 2. Again, 48545 = 46625 + the previous terms (1578 + 270 + 72).

A054540, A060525, A060526, A060527, A060528, A060529, A001149, A000045.

Recurrence: The next term equals the current term plus one or more of the previous terms: a(n+1) = a(n) + a(n-x)... + a(n-y)... + a(n-z), etc.

A001856 A self-generating sequence: every positive integer occurs as a(i)-a(j) for a unique pair i,j.

Original entry on oeis.org

1, 2, 4, 8, 16, 21, 42, 51, 102, 112, 224, 235, 470, 486, 972, 990, 1980, 2002, 4004, 4027, 8054, 8078, 16156, 16181, 32362, 32389, 64778, 64806, 129612, 129641, 259282, 259313, 518626, 518658, 1037316, 1037349, 2074698, 2074734, 4149468

Offset: 1

N. J. A. Sloane

This is a B_2 sequence. More economical recursion: a(1)=1, a(2n)=2a(2n-1), a(2n+1)=a(2n)+r(n), where r(n) is the smallest positive integer not of the form a(j)-a(i) with 1<=iA247556. - Thomas Ordowski, Sep 28 2014

R. K. Guy, Unsolved Problems in Number Theory, E25.
W. Sierpiński, Elementary Theory of Numbers. Państ. Wydaw. Nauk., Warsaw, 1964, p. 444.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

T. D. Noe, Table of n, a(n) for n = 1..1000
R. L. Graham, Problem E1910, Amer. Math. Monthly, 73 (1966), 775.
R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 3-20.
R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 3-20. [Annotated scanned copy]
R. K. Guy and N. J. A. Sloane, Correspondence, 1988.
M. Hall, Cyclic projective planes, Duke Math. J., 4 (1947), 1079-1090.
C. B. A. Peck, Remark on Problem E1910, Amer. Math. Monthly, 75 (1968), 80-81.
W. Sierpiński, Elementary Theory of Numbers, Warszawa 1964.
N. J. A. Sloane, Handwritten notes on Self-Generating Sequences, 1970 (note that A1148 has now become A005282)

Cf. A054540, A004978, A247556.

a[1] = 1; a[2] = 2; a[n_?OddQ] := a[n] = 2*a[n-1]; a[n_?EvenQ] := a[n] = a[n-1] + r[(n-2)/2]; r[n_] := ( diff = Table[a[j] - a[i], {i, 1, 2*n+1}, {j, i+1, 2*n+1}] // Flatten // Union; max = diff // Last; notDiff = Complement[Range[max], diff]; If[notDiff == {}, max+1, notDiff // First]); Table[a[n], {n, 1, 39}] (* Jean-François Alcover, Dec 31 2012 *)

a(1)=1, a(2)=2, a(2n+1) = 2a(2n), a(2n+2) = a(2n+1) + r(n), where r(n) = smallest positive number not of form a(j) - a(i) with 1 <= i < j <= 2n+1.

More terms from Larry Reeves (larryr(AT)acm.org), Sep 14 2000

A061918 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 5/4 and 8/5 which generate two complementary tones of musical harmony, the Major 3rd (5/4) and the Minor 6th (8/5).

Original entry on oeis.org

1, 2, 3, 16, 19, 22, 25, 28, 59, 87, 146, 351, 497, 643, 2718, 3361, 4004, 8651, 12655, 21306, 55267, 76573, 97879, 489395, 1055363, 1153242, 1251121, 1349000, 1446879, 1544758, 1642637, 1740516, 1838395, 1936274, 5808822, 7647217

Offset: 1

Mark William Rankin (MarkRankin95511(AT)Yahoo.com), May 15 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to 7647217. The numerical value of each term represents a musical scale based on an equal division of the octave. 19, for example, signifies the scale which is formed by dividing the octave into 19 equal parts. Among the terms listed, the self-accumulating nature (recurrence) in this sequence breaks down down five times, between the 3rd and 4th terms, between the 14th and 15th terms, between the 20th and 21st terms, between the 23rd and 24th terms and between the 24th and 25th terms. In later sequences, this pair of target ratios will appear in combination with other pairs of target ratios, resulting in new, different (and often recurrent), composite sequences. The examples of proper recurrence which do occur in this sequence are of the same type as is seen in sequences A054540, A060526, A060527, A060233.

A054540, A060525, A060526, A060527, A060528, A060529, A060233, A061416.

A117554 Equal divisions of the octave of decreasing 5-limit Pepper ambiguity.

Original entry on oeis.org

1, 3, 12, 19, 34, 53, 118, 441, 612, 730, 1171, 1783, 2513, 4296, 25164, 52841, 73709, 78005

Offset: 0

Gene Ward Smith, Mar 28 2006

We may define the p-limit Pepper ambiguity, for any odd prime p, as the maximum of the ratios of the errors of the nearest approximation to the members of the p-limit tonality diamond to the next nearest. In the 5-limit, that means we look at the ratios of the errors for the nearest approximations to 3/2, 5/4 and 5/3 to the next nearest.

The 3-limit version of this is A005664, so in some sense this is a generalization of that. However it is also very closely related to A054540.

Wikipedia, Tonality diamond

Cf. A117555, A117556, A117557, A117558, A117559, A005664, A054540.

A061416 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 11/8 and 16/11 which generate two complementary musical tones.

Original entry on oeis.org

1, 2, 6, 7, 9, 11, 13, 24, 37, 505, 542, 579, 616, 653, 690, 727, 764, 801, 838, 875, 912, 949, 986, 1935, 2921, 4856, 11647, 16503, 148527, 181533, 214539, 219395, 235898, 252401, 268904, 285407, 301910, 318413, 334916, 351419, 367922, 384425

Offset: 1

Mark William Rankin (MarkRankin95511(AT)Yahoo.com), May 02 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to 384425. The numerical value of each term represents a musical scale based on an equal division of the octave. 24, for example, signifies the scale of quartertones which is formed by dividing the octave into 24 equal parts. The recurrence in this sequence breaks down three times, between the 2nd and 3rd terms, between the 9th and 10th terms and between the 28th and 29th terms, but the sequence is of interest because shows the terms generated when this pair of target ratios stands alone. Later, in other sequences, this pair of target ratios will appear in combination with other pairs of target ratios, resulting in new, different, composite sequences. The examples of proper recurrence which do occur in this sequence are of the same type as is seen in sequences A054540, A060526, A060527, A060529 and A060233.

A054540, A060526, A060527, A060529, A060233, A001149 and A000045.

A117539 Integrals of the absolute value of the Z function between successive zeros greater than or equal to the integral corresponding to 12. If we define the normalized Z function by z(x) = Z(2Pix/log(2)), then the 33rd and 34th zeros are approximately 11.82 and 12.25. Integrating |z(x)| between these values gives a quantity I and the above sequence is defined as the midpoints of all successive zeros of z(x) such that the integral of |z(x)| is greater than or equal to I.

Original entry on oeis.org

12, 19, 31, 41, 46, 53, 58, 65, 72, 77, 87, 94, 99, 103, 111

Offset: 0

Gene Ward Smith, Mar 27 2006

The reason for the choice of 12 as a starting point is from musical practice; 12 is the standard equal division of the octave of Western music. The subsequent values where this integral is greater than it is for 12 are also equal divisions. While all the values tabulated are such that the integer of the integer sequence is actually contained in the interval between two successive zeros, it must eventually happen that a counterexample would be found. Another interesting question is the density of this sequence; it is not clear if it is increasing in density or not.

Edwards, H. M., Riemann's Zeta-Function, Academic Press, 1974
Titchmarsh, E. C., The Theory of the Riemann Zeta-Function, second revised (Heath-Brown) edition, Oxford University Press, 1986

Andrew Odlyzko, The first 100,000 zeros of the Riemann zeta function, accurate to within 3*10^(-9)
Wikipedia, Z function

Cf. A117536, A117537, A117538, A054540.

A061919 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 6/5 and 5/3 which generate two complementary musical harmonies, the Minor 3rd (6/5) and the Major 6th (5/3).

Original entry on oeis.org

1, 2, 3, 4, 11, 15, 19, 95, 232, 251, 270, 289, 308, 327, 346, 365, 384, 403, 422, 1285, 1707, 2129, 3836, 19180, 28981, 32817, 36653, 40489, 44325, 48161, 51997, 259985, 3591629, 3643626, 3695623, 3747620, 3799617, 3851614, 3903611, 3955608

Offset: 1

Mark William Rankin (MarkRankin95511(AT)Yahoo.com), May 15 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to 3955608. The numerical value of each term represents a musical scale based on an equal division of the octave. 19, for example, signifies the scale formed by dividing the octave into 19 equal parts. Within the terms shown, the self-accumulating nature of this sequence breaks down five times, between the 4th and 5th terms, between the 7th and 8th terms, between the 8th and 9th terms, between the 23rd and 24th terms and between the 32nd and 33rd terms, but the sequence is of interest because it shows the terms generated when this pair of target ratios stands alone.

Later, in other sequences, this pair of target ratios will appear in combination with other pairs of target ratios, resulting in new, different (and often recurrent), composite sequences. The examples of proper recurrence which do occur in this sequence are of the same type which is seen in sequences A054540, A060526, A060527 and A060233.

A054540, A060525, A060526, A060527, A060528, A060529, A060233, A061416, A061918.

A061920 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the 7 pairs of complementary target ratios needed to express the 12 unsymmetrical steps of the untempered (Just Intonation) scale known as the Duodene: 3/2 and 4/3, 5/4 and 8/5, 6/5 and 5/3, 9/8 and 16/9, 10/9 and 9/5, 16/15 and 15/8 and 45/32 and 64/45.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 19, 22, 31, 34, 41, 53, 118, 171, 289, 323, 376, 441, 494, 559, 612, 1171, 1783, 2513, 3684, 4296, 12888, 16572, 20868, 25164, 44249, 48545, 52841, 57137, 69413, 73709, 78005, 151714, 229719, 307724, 537443, 714321

Offset: 1

Mark William Rankin (MarkRankin95511(AT)yahoo.com), May 15 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to 714321. The numerical value of each term represents a musical scale based on an equal division of the octave. The term 12, for example, signifies the scale which is formed by dividing the octave into 12 equal parts.

			118 = 53 + [34 + 31]; Again, 69413 = 57137 + [4296 + 3684 + 2513 + 1783].

A054540, A060525, A060526, A060527, A060528, A060529, A060233, A061918, A061919.

Recurrence Rule: The next term equals the current term plus one or more previous terms: a(n+1) = a(n) + a(n-x)... + a(n-y)... + a(n-z), etc.

A018065 Powers of fourth root of 7 rounded up.

Original entry on oeis.org

1, 2, 3, 5, 7, 12, 19, 31, 49, 80, 130, 211, 343, 558, 908, 1477, 2401, 3906, 6353, 10333, 16807, 27338, 44468, 72330, 117649, 191366, 311270, 506305, 823543, 1339556, 2178890, 3544132, 5764801, 9376891

Offset: 0

N. J. A. Sloane

nonn

Cf. A054540.

A061921 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the 11 pairs of target ratios needed to express the 22 steps of the theoretical Hindu scale known as the 22 Srutis: 45/32 and 64/45, 27/20 and 40/27, 4/3 and 3/2, 81/64 and 128/81, 5/4 and 8/5, 6/5 and 5/3, 32/27 and 27/16, 9/8 and 16/9, 10/9 and 9/5, 16/15 and 15/8, 256/243 and 243/128.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 28, 29, 30, 32, 34, 37, 39, 40, 41, 53, 118, 171, 323, 335, 376, 388, 441, 494, 506, 559, 612, 1171, 1783, 2513, 3072, 3125, 3684, 4296, 12276, 16572, 20868, 40565, 44861, 48545, 52841, 57137, 61433, 69413, 73709

Offset: 1

Mark William Rankin (MarkRankin95511(AT)Yahoo.com), May 15 2001

nonn

The sequence was found by a computer search of all the equal divisions of the octave from 1 to 73709. The numerical value of each term represents a musical scale based on an equal division of the octave. The term 32, for example, signifies the scale which is formed by dividing the octave into 32 equal parts.

			118 = 53 + [34 + 31]; Again, 229719 = 78005 + [73709 + 69413 + 4296 + 3684 + 612].

A054540, A060525, A060526, A060527, A060528, A060529, A060233, A061416, A061918, A061919, A061920.

Recurrence rule: The next term equals the current term plus one or more previous terms: a(n+1) = a(n) + a(n-x)... + a(n-y)... + a(n-z), etc.

cp's OEIS Frontend

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A001856 A self-generating sequence: every positive integer occurs as a(i)-a(j) for a unique pair i,j.

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A061918 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 5/4 and 8/5 which generate two complementary tones of musical harmony, the Major 3rd (5/4) and the Minor 6th (8/5).

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A117554 Equal divisions of the octave of decreasing 5-limit Pepper ambiguity.

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A061416 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 11/8 and 16/11 which generate two complementary musical tones.

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A061919 A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the pair of ratios 6/5 and 5/3 which generate two complementary musical harmonies, the Minor 3rd (6/5) and the Major 6th (5/3).

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A018065 Powers of fourth root of 7 rounded up.

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