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 1-10 of 25 results. Next

A253557 a(1) = 0; after which, a(2n) = 1 + a(n), a(2n+1) = a(A268674(2n+1)).

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 4, 2, 2, 2, 3, 1, 3, 1, 5, 3, 2, 2, 4, 1, 2, 2, 4, 1, 4, 1, 3, 4, 2, 1, 5, 2, 3, 3, 3, 1, 3, 3, 4, 3, 2, 1, 4, 1, 2, 2, 6, 2, 4, 1, 3, 4, 3, 1, 5, 1, 2, 2, 3, 2, 3, 1, 5, 3, 2, 1, 5, 3, 2, 3, 4, 1, 5, 3, 3, 5, 2, 2, 6, 1, 3, 2, 4, 1, 4, 1, 4, 4, 2, 1, 4, 1, 4, 2, 5, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 12 2015

Keywords

Comments

Consider the binary trees illustrated in A252753 and A252755: If we start from any n, computing successive iterations of A253554 until 1 is reached (i.e., we are traversing level by level towards the root of the tree, starting from that vertex of the tree where n is located), a(n) gives the number of even numbers encountered on the path (i.e., including both 2 and the starting n if it was even).
This is bigomega (A001222) analog for nonstandard factorization based on the sieve of Eratosthenes (A083221). See A302041 for an omega-analog. - Antti Karttunen, Mar 31 2018

Links

Crossrefs

Essentially, one more than A253559.
Primes, A000040, gives the positions of ones.
Cf. A000079, A000120, A080791, A252753, A252754, A252755, A252756, A253554, A253555, A253556, A253558, A302037, A302041, A302042.
Differs from A001222 for the first time at n=21, where a(21) = 3, while A001222(21) = 2.

Programs

Formula

a(1) = 0; after which, a(2n) = 1 + a(n), a(2n+1) = a(A268674(2n+1)).
a(n) = A253555(n) - A253556(n).
a(n) = A000120(A252754(n)). [Binary weight of A252754(n).]
Other identities.
For all n >= 0:
a(2^n) = n.
For all n >= 2:
a(n) = A080791(A252756(n)) + 1. [One more than the number of nonleading 0-bits in A252756(n).]
From Antti Karttunen, Apr 01 2018: (Start)
a(1) = 0; for n > 1, a(n) = 1 + a(A302042(n)).
a(n) = A001222(A250246(n)).
(End)

Extensions

Definition (formula) corrected by Antti Karttunen, Mar 31 2018

A252754 Inverse of "Tree of Eratosthenes" permutation: a(1) = 0, after which, a(2n) = 1 + 2*a(n), a(2n+1) = 2 * a(A268674(2n+1)).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 8, 7, 6, 9, 16, 11, 32, 17, 10, 15, 64, 13, 128, 19, 14, 33, 256, 23, 12, 65, 18, 35, 512, 21, 1024, 31, 22, 129, 20, 27, 2048, 257, 34, 39, 4096, 29, 8192, 67, 30, 513, 16384, 47, 24, 25, 26, 131, 32768, 37, 28, 71, 38, 1025, 65536, 43, 131072, 2049, 66, 63, 36, 45, 262144, 259, 46, 41, 524288, 55, 1048576, 4097, 130, 515, 40
Offset: 1

Views

Author

Antti Karttunen, Jan 02 2015

Keywords

Links

Crossrefs

Inverse: A252753.
Fixed points of a(n)+1: A253789.
Cf. A250470, A253556, A253557, A253558, A253559, A268674, A302041.
Similar permutations: A156552, A252756, A054429, A250246, A269388.
Differs from A156552 for the first time at n=21, where a(21) = 14, while A156552(21) = 18.

Programs

Formula

a(1) = 0, after which, a(2n) = 1 + 2*a(n), a(2n+1) = 2 * a(A268674(2n+1)).
As a composition of related permutations:
a(n) = A054429(A252756(n)).
a(n) = A156552(A250246(n)).
From Antti Karttunen, Mar 31 2018: (Start)
A000120(a(n)) = A253557(n).
A069010(a(n)) = A302041(n).
A132971(a(n)) = A302050(n).
A106737(a(n)) = A302051(n).
(End)

Extensions

Name edited and formula corrected by Antti Karttunen, Mar 31 2018

A269171 Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A269379(a(A268674(2n+1))).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 23, 20, 21, 22, 25, 24, 19, 26, 27, 28, 29, 30, 37, 32, 33, 34, 35, 36, 41, 46, 39, 40, 43, 42, 47, 44, 45, 50, 53, 48, 31, 38, 51, 52, 61, 54, 49, 56, 57, 58, 67, 60, 71, 74, 63, 64, 65, 66, 77, 68, 69, 70, 83, 72, 89, 82, 75, 92, 59, 78, 91, 80, 81, 86, 97, 84, 79, 94, 87, 88, 107, 90, 85, 100
Offset: 1

Views

Author

Antti Karttunen, Mar 03 2016

Keywords

Links

Crossrefs

Inverse: A269172.
Cf. A000035, A003309, A008578, A055396, A078898, A268674, A255127, A269379.
Related or similar permutations: A260741, A260742, A269355, A269357, A255421, A252754, A252756, A269385, A269387.
Cf. also A269393 (a(3n)/3) and A269395.
Differs from A255407 for the first time at n=38, where a(38) = 46, while A255407(38) = 38.

Formula

a(1) = 1, then after for even n, a(n) = 2*a(n/2), and for odd n, a(n) = A269379(a(A268674(n))).
a(1) = 1, for n > 1, a(n) = A255127(A055396(n), a(A078898(n))).
As a composition of other permutations:
a(n) = A269385(A252756(n)).
a(n) = A269387(A252754(n)).
Other identities. For all n >= 1:
A000035(a(n)) = A000035(n). [Preserves the parity of n.]
a(A008578(n)) = A003309(n). [Maps noncomposites to Ludic numbers.]

A269866 Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = 1 + 2*a(A268674(2n+1)-1).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 9, 8, 7, 10, 13, 12, 21, 18, 11, 16, 25, 14, 33, 20, 19, 26, 29, 24, 17, 42, 15, 36, 53, 22, 73, 32, 27, 50, 37, 28, 45, 66, 43, 40, 57, 38, 81, 52, 23, 58, 77, 48, 49, 34, 51, 84, 117, 30, 41, 72, 67, 106, 169, 44, 213, 146, 39, 64, 85, 54, 89, 100, 59, 74, 109, 56, 149, 90, 35, 132, 101, 86, 113, 80, 31
Offset: 1

Views

Author

Antti Karttunen, Mar 12 2016

Keywords

Links

Crossrefs

Inverse: A269865.
Cf. A268674.
Related or similar permutations: A269867, A249813, A252756, A270196.
Differs from similarly constructed A246376 for the first time at n=21, where a(21) = 19, instead of 15.

Formula

a(1) = 1, a(2n) = 2*a(n), a(2n+1) = 1 + 2*a(A268674(2n+1)-1).

A269867 Self-inverse permutation of natural numbers: a(1) = 1, for even n, a(n) = A250469(1+a(n/2)), for odd n, a(n) = 2*a(A268674(n)-1).

Original entry on oeis.org

1, 3, 2, 9, 6, 5, 18, 27, 4, 11, 10, 15, 22, 23, 12, 81, 30, 7, 162, 33, 36, 13, 14, 45, 54, 29, 8, 69, 26, 17, 138, 243, 20, 37, 46, 21, 34, 167, 44, 99, 42, 41, 198, 39, 24, 35, 82, 135, 90, 91, 60, 87, 70, 25, 66, 207, 324, 65, 174, 51, 130, 149, 72, 729, 58, 55, 102, 111, 28, 53, 110, 63, 106, 77, 108, 501, 74, 115, 126, 297, 16, 47
Offset: 1

Views

Author

Antti Karttunen, Mar 12 2016

Keywords

Links

Crossrefs

Cf. A250469, A268674.
Similar permutations: A269865, A269866, A270197.

Formula

a(1) = 1, a(2n) = A250469(1+a(n)), a(2n+1) = 2*a(A268674(2n+1)-1).

A269356 Permutation of natural numbers: a(n) = A268674(A269379(n)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 17, 10, 11, 12, 13, 14, 15, 16, 19, 18, 29, 20, 25, 22, 9, 24, 23, 26, 27, 28, 31, 30, 21, 32, 73, 34, 53, 36, 37, 38, 39, 40, 41, 42, 43, 44, 107, 46, 47, 48, 33, 50, 51, 52, 59, 54, 71, 56, 137, 58, 101, 60, 61, 62, 63, 64, 109, 66, 67, 68, 121, 70, 35, 72, 97, 74, 75, 76, 79, 78, 131, 80, 197
Offset: 1

Views

Author

Antti Karttunen, Mar 03 2016

Keywords

Examples

			For n=9 we first find what number is below 9 in square array A255127, which is 19, then we find what number is above 19 in square array A083221, which is 17, thus a(9) = 17.

Links

Crossrefs

Inverse: A269355.
Cf. A268674, A269379.
Cf. also arrays A083221 & A255127.
More recursed variant: A269358. Cf. also permutations A266646, A255408, A269172.

Programs

Formula

a(n) = A268674(A269379(n)).
Other identities. For all n >= 1:
a(2n) = 2n. [Fixes the even numbers.]

A269358 Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A268674(A269379(2n+1)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 17, 10, 11, 12, 13, 14, 15, 16, 19, 34, 29, 20, 25, 22, 9, 24, 23, 26, 27, 28, 31, 30, 21, 32, 73, 38, 53, 68, 37, 58, 39, 40, 41, 50, 43, 44, 107, 18, 47, 48, 33, 46, 51, 52, 59, 54, 71, 56, 137, 62, 101, 60, 61, 42, 63, 64, 109, 146, 67, 76, 121, 106, 35, 136, 97, 74, 75, 116, 79, 78, 131, 80, 197
Offset: 1

Views

Author

Antti Karttunen, Mar 03 2016

Keywords

Comments

This is a variant of A269356, from which it differs for the first time at n=18.

Links

Crossrefs

Inverse: A269357.
Cf. A000035, A268674, A269379, A269356, A269171.

Formula

a(1) = 1, after which, for even n, a(n) = 2*a(n/2) and for odd n, a(n) = A269356(n) = A268674(A269379(n)).
Other identities. For all n >= 1:
A000035(a(n)) = A000035(n). [This permutation preserves the parity of n.]

A269852 Permutation of natural numbers: a(1) = 0, after which, a(2n) = A087686(1+a(n)), a(2n+1) = A088359(a(A268674(2n+1))).

Original entry on oeis.org

0, 1, 3, 2, 6, 7, 11, 4, 5, 14, 20, 15, 37, 26, 13, 8, 70, 12, 135, 30, 9, 47, 264, 31, 10, 85, 25, 57, 521, 29, 1034, 16, 28, 156, 23, 27, 2059, 292, 46, 62, 4108, 21, 8205, 105, 17, 557, 16398, 63, 19, 24, 22, 191, 32783, 56, 18, 120, 55, 1079, 65552, 61, 131089, 2114, 84, 32, 44, 60, 262162, 348, 59, 53
Offset: 1

Views

Author

Antti Karttunen, Mar 07 2016

Keywords

Comments

Note the indexing: Domain starts from 1, range from 0.

Links

Crossrefs

Inverse: A269851.
Cf. A004001, A087686, A088359, A268674.
Related or similar permutations: A252756, A267112, A269856.

Formula

a(1) = 0; after which, for even n, a(n) = A087686(1+a(n/2)), and for odd n, a(n) = A088359(a(A268674(n))).
Other identities. For all n >= 1:
a(2^n) = 2^(n-1).
As a composition of other permutations:
a(n) = A267112(A252756(n)).

A269856 Permutation of natural numbers: a(1) = 0, a(2) = 1, a(2n) = A001969(1+a(n)), a(2n+1) = A000069(1+a(A268674(2n+1))).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 8, 6, 7, 9, 16, 10, 32, 17, 11, 12, 64, 15, 128, 18, 13, 33, 256, 20, 14, 65, 19, 34, 512, 23, 1024, 24, 21, 129, 22, 30, 2048, 257, 35, 36, 4096, 27, 8192, 66, 25, 513, 16384, 40, 28, 29, 31, 130, 32768, 39, 26, 68, 37, 1025, 65536, 46, 131072, 2049, 67, 48, 38, 43, 262144, 258, 41, 45, 524288, 60
Offset: 1

Views

Author

Antti Karttunen, Mar 07 2016

Keywords

Comments

Note the indexing: Domain starts from 1, range from 0.

Links

Crossrefs

Inverse: A269855.
Cf. A000069, A001969, A268674.
Related or similar permutations: A003188, A252756, A269852.

Formula

a(1) = 0, a(2) = 1, a(2n) = A001969(1+a(n)), a(2n+1) = A000069(1+a(A268674(2n+1))).
As a composition of other permutations:
a(n) = A003188(A252756(n)).

A269858 Permutation of natural numbers: a(1) = 1, a(2n) = A065090(1+a(n)), a(2n+1) = A000040(a(A268674(2n+1))).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 11, 8, 7, 9, 31, 10, 127, 18, 13, 14, 709, 12, 5381, 15, 19, 45, 52711, 16, 17, 165, 23, 27, 648391, 21, 9737333, 22, 29, 856, 41, 20, 174440041, 6185, 61, 24, 3657500101, 28, 88362852307, 63, 43, 58644, 2428095424619, 25, 59, 26, 37, 212, 75063692618249, 34, 67, 39, 47
Offset: 1

Views

Author

Antti Karttunen, Mar 06 2016

Keywords

Comments

Terms for prime positions copied from A007097.

Links

Crossrefs

Inverse: A269857.
Cf. A000040, A007097, A065090, A268674.
Related or similar permutations: A237739, A252756, A269848.

Formula

a(1) = 1, a(2) = 2, for n > 2, if n is even, a(n) = A002808(a(n/2)-1), and for odd n, a(n) = A000040(a(A268674(n))).
As a composition of other permutations:
a(n) = A237739(A252756(n)).
Other identities. For all n >= 1:
a(A000040(n)) = A007097(n). [Maps primes to the primeth recurrence.]
Showing 1-10 of 25 results. Next

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