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.

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A245614 Permutation of natural numbers: a(1)=1; thereafter, if n is k-th number whose greatest prime factor has an odd index [i.e., n = A244991(k)], a(n) = A026424(a(k)), otherwise, when n is k-th number whose greatest prime factor has an even index [i.e., n = A244990(1+k)], a(n) = A028260(1+a(k)).

Original entry on oeis.org

1, 2, 4, 3, 7, 6, 10, 5, 9, 12, 11, 16, 15, 24, 18, 8, 17, 14, 22, 20, 26, 19, 29, 25, 28, 36, 35, 55, 39, 44, 31, 13, 30, 27, 21, 38, 34, 51, 46, 42, 37, 57, 40, 47, 32, 52, 45, 62, 56, 50, 68, 60, 82, 81, 67, 121, 86, 93, 105, 72, 65, 79, 33, 59, 64, 23, 53, 48, 41, 58, 49, 85, 71, 77, 66, 111, 99
Offset: 1

Views

Author

Antti Karttunen, Jul 27 2014

Keywords

Comments

This shares with the permutation A122111 the property that each term of A244990 is mapped to a unique term of A028260 and each term of A244991 is mapped to a unique term of A026424.

Crossrefs

Formula

a(1) = 1, and for n > 1, if A244992(n) = 1, a(n) = A026424(a(A244989(n))), otherwise a(n) = A028260(1+a(A244988(n)-1)).
As a composition of related permutations:
a(n) = A245604(A244321(n)).
For all n >= 1, A244992(n) = A066829(a(n)).

A269864 Permutation of natural numbers: a(1) = 1, a(2n) = A269360(a(n)), a(2n+1) = A250469(1+a(n)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 9, 10, 7, 8, 15, 16, 11, 26, 27, 28, 13, 12, 21, 22, 25, 36, 45, 46, 19, 14, 33, 76, 65, 66, 81, 82, 31, 18, 39, 34, 17, 56, 63, 64, 29, 50, 75, 106, 41, 116, 135, 136, 53, 24, 57, 40, 35, 86, 99, 226, 143, 120, 195, 196, 71, 206, 243, 244, 89, 38, 93, 52, 23, 96, 117, 100, 77, 20, 51, 166, 145, 156, 189, 190, 119, 32, 87
Offset: 1

Views

Author

Antti Karttunen, Mar 13 2016

Keywords

Comments

This sequence can be represented as a binary tree. When the parent contains n, the left hand child contains A269360(n) [= 1+A250469(n)] and the right hand child contains A250469(1+n):
1
|
................../ \..................
2 3
4......../ \........5 6......../ \........9
/ \ / \ / \ / \
/ \ / \ / \ / \
/ \ / \ / \ / \
10 7 8 15 16 11 26 27
28 13 12 21 22 25 36 45 46 19 14 33 76 65 66 81
etc.

Crossrefs

Inverse: A269863.
Cf. also A269865, A269866, A269867.
Differs from similarly constructed A245606 for the first time at n=15, where a(15)=27 instead of 21.

Formula

a(1) = 1, a(2n) = 1 + A250469(a(n)), a(2n+1) = A250469(1+a(n)).

A245712 Permutation of natural numbers, odd bisection of A245706 incremented by one and halved: a(n) = (1+A245706((2*n)-1)) / 2.

Original entry on oeis.org

1, 2, 3, 6, 4, 14, 5, 38, 10, 8, 26, 330, 18, 46, 283, 42, 11, 34, 7, 50, 70, 22, 17, 326, 37, 58, 27, 32, 53, 9590, 554, 4438, 278, 174, 9, 16, 15, 142, 25, 226, 146, 658, 105, 310, 1190, 806, 1770, 524, 51, 5258, 66, 5302, 35, 518, 17739, 1054, 19030, 542, 5550, 8054, 35498, 4434, 29, 810, 1106, 72, 75, 28, 63, 166, 83, 150, 44
Offset: 1

Views

Author

Antti Karttunen, Jul 30 2014

Keywords

Crossrefs

Inverse: A245711.

Programs

Formula

a(n) = (1+A245706((2*n)-1)) / 2.
Previous Showing 11-13 of 13 results.