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.

A072786 Differences between A072782 and A072739.

Original entry on oeis.org

0, 0, 0, -1, 0, 0, 1, 0, 0, 0, -1, -1, 0, 0, 0, 1, 1, 0, 0, 0, 0, -1, -1, -1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, -1, -1, -1, -1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -1, -1, 0
Offset: 0

Views

Author

Antti Karttunen, Jun 12 2002

Keywords

Programs

A072735 Simple triangle-stretching N X N -> N bijection: Inverse of A072734, variant of A072733.

Original entry on oeis.org

0, 1, 2, 3, 5, 9, 10, 6, 14, 20, 21, 15, 4, 27, 35, 36, 28, 7, 8, 44, 54, 55, 45, 11, 13, 19, 65, 77, 78, 66, 22, 16, 26, 34, 90, 104, 105, 91, 37, 29, 12, 43, 53, 119, 135, 136, 120, 56, 46, 17, 18, 64, 76, 152, 170, 171, 153, 79, 67, 23, 25, 33, 89, 103, 189, 209, 210
Offset: 0

Views

Author

Antti Karttunen, Jun 12 2002

Keywords

Crossrefs

Inverse: A072734, projections: A072781 & A072782, variant of the same theme: A072733. Cf. also A001477 and its projections A025581 & A002262.

Programs

  • Scheme
    (define (A072735 n) (packA072735 (A025581 n) (A002262 n)))
    (define (packA001477 x y) (/ (+ (expt (+ x y) 2) x (* 3 y)) 2))
    (define (packA072735 x y) (cond ((<= x y) (let ((half-x (floor->exact (/ x 2)))) (packA001477 half-x (+ half-x (* 2 (- y (* 2 half-x))) (modulo x 2) (if (and (eq? x y) (even? x)) 0 -1))))) (else (let ((half-y (floor->exact (/ y 2)))) (packA001477 (+ half-y (* 2 (- (-1+ x) (* 2 half-y))) (modulo y 2) (if (and (eq? x (1+ y)) (even? y)) 1 0)) half-y)))))

A072739 Y-projection of the tabular N X N -> N bijection A072733.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 0, 2, 3, 2, 1, 3, 4, 3, 2, 0, 2, 4, 5, 4, 3, 1, 3, 5, 6, 5, 4, 3, 0, 2, 4, 6, 7, 6, 5, 4, 1, 3, 5, 7, 8, 7, 6, 5, 4, 0, 2, 4, 6, 8, 9, 8, 7, 6, 5, 1, 3, 5, 7, 9, 10, 9, 8, 7, 6, 5, 0, 2, 4, 6, 8, 10, 11, 10, 9, 8, 7, 6, 1, 3, 5, 7, 9, 11, 12, 11, 10, 9, 8, 7, 6, 0, 2, 4, 6, 8, 10, 12, 13
Offset: 0

Views

Author

Antti Karttunen, Jun 12 2002

Keywords

Crossrefs

The X-projection is A072738. Composition of A002262 and A072732. A072786(n) = A072782(n)-A072739(n).

Programs

A072781 X-projection of the tabular N X N -> N bijection A072735.

Original entry on oeis.org

0, 1, 0, 2, 2, 1, 2, 3, 2, 0, 3, 4, 4, 3, 1, 3, 4, 5, 4, 2, 0, 4, 5, 6, 6, 5, 3, 1, 4, 5, 6, 7, 6, 4, 2, 0, 5, 6, 7, 8, 8, 7, 5, 3, 1, 5, 6, 7, 8, 9, 8, 6, 4, 2, 0, 6, 7, 8, 9, 10, 10, 9, 7, 5, 3, 1, 6, 7, 8, 9, 10, 11, 10, 8, 6, 4, 2, 0, 7, 8, 9, 10, 11, 12, 12, 11, 9, 7, 5, 3, 1, 7, 8, 9, 10, 11, 12, 13
Offset: 0

Views

Author

Antti Karttunen, Jun 12 2002

Keywords

Crossrefs

The Y-projection is A072782. Composition of A025581 & A072734. A072785(n) = A072781(n)-A072738(n).

Programs

Showing 1-4 of 4 results.