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.

Previous Showing 51-53 of 53 results.

A153010 Indices of A153007 where the entry equals zero.

Original entry on oeis.org

0, 1, 2, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535, 131071, 262143, 524287, 1048575, 2097151, 4194303, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 536870911, 1073741823, 2147483647, 4294967295
Offset: 0

Views

Author

Omar E. Pol, Dec 21 2008

Keywords

Comments

It appears that this sequence is also the union of 2 and A000225. - Omar E. Pol, Mar 03 2011

Links

Crossrefs

Cf. A000217, A000225, A139250, A153006, A153007.

Formula

Conjectures from Colin Barker, Nov 24 2019: (Start)
G.f.: x*(1 - x - x^2 + 2*x^3) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>4.
a(n) = 2^(n-1) - 1 for n>2.
(End)

Extensions

More terms a(7)-a(18) from Sean A. Irvine, Feb 22 2011
More terms a(19)-a(33) from Omar E. Pol, Mar 03 2011

A159801 Partial sums of A153001.

Original entry on oeis.org

4, 11, 20, 30, 45, 67, 88, 102, 117, 140, 168, 203, 255, 319, 368, 390, 405, 428, 456, 491, 543, 608, 664, 707, 760, 834, 925, 1047, 1215, 1391, 1504, 1542, 1557, 1580, 1608, 1643, 1695, 1760, 1816, 1859, 1912, 1986, 2077, 2199, 2367, 2544, 2664, 2723, 2776, 2850
Offset: 1

Views

Author

Omar E. Pol, May 18 2009

Keywords

Links

Crossrefs

Cf. A139250, A139251, A152980, A153001, A153006.

Extensions

More terms from Jinyuan Wang, Mar 15 2020

A220499 Number of line segments in an H tree with n levels that have no correspondence with the toothpicks of the toothpick structure of A139250 after n-th stage.

Original entry on oeis.org

0, 0, 0, 0, 4, 16, 40, 92, 212, 464, 968, 1980, 4016, 8096, 16260, 32612, 65364, 130896, 261960, 524092, 1048368, 2096928, 4194052, 8388324, 16776912, 33554112, 67108516, 134217344, 268435032, 536870428, 1073741252, 2147482996, 4294966612, 8589933904
Offset: 0

Views

Author

Omar E. Pol, Feb 16 2013

Keywords

Comments

More generally, differences between A000225 and A139250.

Examples

			For n = 0..3, the number of line segments in the H tree equals the number of toothpicks in the toothpick structure of A139250, so a(n) = 0, if 0 <= n <= 3. Note that there is a correspondence between every element from the two structures. For n = 4 the H tree contains 15 line segments, on the other hand the toothpick structure contains only 11 toothpicks. There are four line segments in the H tree that have no correspondence with the toothpicks of the toothpicks structure. They are the four line segments of the last generation that are closer to the center of the H tree, so a(4) = 4.

Links

Crossrefs

Cf. A000079, A000225, A139250, A139251, A152978, A152980, A153000, A153006.

Formula

a(n) = A000225(n) - A139250(n).
Previous Showing 51-53 of 53 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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