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 1-3 of 3 results.

A306219 Records in A096004.

Original entry on oeis.org

1, 4, 8, 16, 24, 32, 40, 48, 64, 80, 96, 112, 128, 144, 160, 208, 215, 256, 272, 280, 311, 320, 335, 395, 400, 430, 455, 527, 535, 575, 635, 640, 670, 695, 755, 775, 815, 895, 935, 1055, 1175, 1355, 1375, 1415, 1475, 1495, 1535, 1615, 1655, 1735, 1775, 1895
Offset: 1

Views

Author

Peter Kagey, Jan 30 2019

Keywords

Crossrefs

Cf. A096004.

A284385 Number of fixed convex n-iamonds (or polyiamonds with n cells).

Original entry on oeis.org

2, 3, 6, 8, 6, 7, 12, 15, 8, 9, 18, 18, 8, 15, 24, 23, 12, 12, 24, 30, 12, 17, 36, 31, 14, 21, 30, 30, 18, 24, 42, 42, 14, 21, 48, 38, 14, 33, 48, 45, 24, 18, 42, 54, 24, 35, 66, 48, 20, 36, 48, 44, 24, 40, 72, 63, 18, 27, 72, 60, 26, 51, 66, 62, 36, 30, 60
Offset: 1

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Author

Rémy Sigrist, Mar 26 2017

Keywords

Comments

Also, the number of ways to write n as p^2-q^2-r^2-s^2 with 0 <= min(q, r, s) and max(q, r, s) < n and max(q+r, r+s, s+q) <= n.

Examples

			See Links section.

Links

Crossrefs

Cf. A000577, A001420, A096004.

A387209 Number of convex polygons with perimeter n on the regular triangular lattice, not counting rotations and reflections as distinct.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 3, 2, 4, 4, 6, 5, 10, 7, 12, 11, 16, 13, 22, 17, 26, 23, 32, 27, 41, 33, 47, 42, 56, 48, 68, 57, 77, 69, 89, 78, 105, 90, 117, 106, 133, 118, 153, 134, 169, 154, 189, 170, 214, 190, 234, 215, 259, 235, 289, 260, 314, 290, 344, 315, 380
Offset: 0

Views

Author

Walter Trump, Aug 22 2025

Keywords

Comments

a(n) also is the number of convex polyiamonds (triangular polyominoes) with perimeter n.

Links

Crossrefs

Cf. A096004 (number of convex polyiamonds with n cells), A284869 (including nonconvex but simply connected polyiamonds with perimeter n), A057729 (including polyiamonds with holes), A036418 (including rotations and reflections but no holes).
Showing 1-3 of 3 results.

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