cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A232359 Positions of peak values in A232221.

Original entry on oeis.org

425, 439, 561, 565, 633, 639, 678, 857, 883, 889, 1148, 2641, 3283, 3590, 3619, 3626, 3628, 4424, 4904, 4917, 4979, 4985, 5061, 7631, 7651, 7676, 7771, 7782, 7801, 7805, 8960, 9340, 9362, 9371, 9414, 9422, 9424, 9428, 9454, 9459, 9773, 10421, 10425, 10450
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 24 2013

Keywords

Comments

max{A232221(a(n)-1),A232221(a(n)+1)} < A232221(a(n)) = A232361(n).

Examples

			Cf. A232361.
		

Programs

  • Haskell
    a232359 n = a232359_list !! (n-1)
    (a232359_list, a232361_list) = unzip $
       f 2 (tail a232221_list) $ zipWith (-) (tail a232221_list) a232221_list
       where f x (y:ys) (u:ws@(v:_))
               | u > 0 && v < 0 = (x, y) : f (x + 1) ys ws
               | otherwise      = f (x + 1) ys ws

A232361 Peak values in A232221.

Original entry on oeis.org

590868, 586496, 392956, 392612, 369532, 371872, 348760, 92820, 98000, 97424, 268428, 7855172, 11351516, 12763068, 12778820, 12778872, 12778940, 14485860, 16971756, 16976632, 17062548, 17065428, 16934020, 33084456, 33100460, 33116544, 32916668, 32921404
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 24 2013

Keywords

Comments

max{A232221(A232359(n)-1),A232221(A232359(n)+1)} < a(n).
First entry < 0: a(77) = -279411084.

Examples

			n = 17: A232359(17) = 3628, a(17) = 12778940:
A232221(3628) = 12778940, whereas A232221(3628-1) = 12778756 and A232221(3628+1) = 12778920 are both less than a(17), with altitude differences 184 and 20. Therefore a(17) is the altitude of a peak in A232221. It can be identified in oeis.org/A232221/graph as top of a foothill.
n = 461: A232359(461) = 373250, a(461) = -2419822248:
A232221(373250) = -2419822248, whereas A232221(373250-1) = -2419823140 and A232221(373250+1) = -2419823192 are both less than a(461), with altitude differences 892 and 944. Therefore a(461) is the altitude of a peak in A232221. It can be identified in Hans Havermann's third plot (< 1.5 million) as the below-axis peak under the 4 of 400000.
		

Programs

  • Haskell
    a232361 n = a232361_list !! (n-1)  -- a232361_list is defined in A232359.

Formula

a(n) = A232221(A232359(n)).

A233973 a(n) = A232221(n)/4.

Original entry on oeis.org

0, 0, 1, 5, 9, 13, 32, 54, 82, 116, 159, 199, 227, 273, 331, 380, 429, 487, 536, 609, 679, 743, 816, 895, 953, 1008, 1042, 1067, 1104, 1180, 1253, 1332, 1429, 1532, 1626, 1675, 1733, 1812, 1921, 2045, 2169, 2317, 2420, 2535, 2656, 2756, 2850, 2953
Offset: 1

Views

Author

Omar E. Pol, Dec 18 2013

Keywords

Crossrefs

Formula

a(n) = (Sum_{i=1..n} (A077068(i)-A077065(i)))/4.

A232342 A077068(n) minus A077065(n).

Original entry on oeis.org

0, 0, 4, 16, 16, 16, 76, 88, 112, 136, 172, 160, 112, 184, 232, 196, 196, 232, 196, 292, 280, 256, 292, 316, 232, 220, 136, 100, 148, 304, 292, 316, 388, 412, 376, 196, 232, 316, 436, 496, 496, 592, 412, 460, 484, 400, 376, 412, 556, 736, 1000, 940, 1012
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 16 2013

Keywords

Comments

All terms are multiples of 4, cf. A008586;
a(n) = A077068(n) - A077065(n).
First term < 0: a(426) = -104.

Crossrefs

Cf. A232221 (partial sums).

Programs

  • Haskell
    a232342 n = a232342_list !! (n-1)
    a232342_list = zipWith (-) a077068_list a077065_list
Showing 1-4 of 4 results.