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 1-7 of 7 results.

A277822 a(n) = index of the column where n is located in array A277880.

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 2, 3, 1, 4, 1, 1, 2, 5, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 4, 1, 1, 2, 5, 1, 1, 2, 1, 2, 3, 1, 6, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 2, 3, 1, 4, 1, 1, 2, 5, 1, 1, 2, 1, 2, 3, 1, 6, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 4, 1, 1, 2, 7, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 4, 1, 1, 2, 1, 2, 3, 1, 4, 1, 1, 2, 5
Offset: 0

Views

Author

Antti Karttunen, Nov 03 2016

Keywords

Comments

Ordinal transform of A277813.
a(n) = 1 + the number of iterations of map k -> A003188(A006068(k)/2) that are required (when starting from k = n) until k is an odious number.

Links

Crossrefs

One more than A277808.
Cf. A000069, A001969, A001511, A003188, A006068, A010059, A010060, A245710, A277813, A277818, A277880.

Formula

a(0) = 0, for n >= 1, a(n) = 1 + (A010059(n)*A001511(n)).
a(0) = 0, for n >= 1, if A010060(n) = 1 [when n is one of the odious numbers, A000069], then a(n) = 1, otherwise a(n) = 1 + a(A003188(A006068(n)/2)).
Other identities. For all n >= 1:
a(n) = 1 + a(floor(n/2)) when A010060(n) = 0.
a(n) = 1+A277808(n).

A246159 Inverse function to the injection A048724.

Original entry on oeis.org

0, 0, 0, 1, 0, 3, 2, 0, 0, 7, 6, 0, 4, 0, 0, 5, 0, 15, 14, 0, 12, 0, 0, 13, 8, 0, 0, 9, 0, 11, 10, 0, 0, 31, 30, 0, 28, 0, 0, 29, 24, 0, 0, 25, 0, 27, 26, 0, 16, 0, 0, 17, 0, 19, 18, 0, 0, 23, 22, 0, 20, 0, 0, 21, 0, 63, 62, 0, 60, 0, 0, 61, 56, 0, 0, 57, 0, 59, 58, 0, 48, 0, 0, 49, 0, 51, 50, 0, 0, 55, 54, 0, 52, 0, 0, 53, 32
Offset: 0

Views

Author

Antti Karttunen, Aug 18 2014

Keywords

Comments

After a(0)=0, sequence has nonzero values a(n) = k at those positions n for which A048724(k) = n and zeros at those positions n which are not present in A048724.
Equally, sequence is obtained when the positive terms of A065620 are replaced with zeros and the sign of the negative terms is reversed.

Links

Crossrefs

Cf. A246160, A006068, A010059, A048724, A065620, A245710.

Programs

  • PARI
    a065620(n) = if(n<3, n, if(n%2, -2*a065620((n - 1)/2) + 1, 2*a065620(n/2)));
a(n) = -!(hammingweight(n)%2)*a065620(n);
for(n=0, 100, print1(a(n),", ")) \\ Indranil Ghosh, Jun 07 2017
  • Python
    def a065620(n): return n if n<3 else 2*a065620(n//2) if n%2==0 else -2*a065620((n - 1)//2) + 1
def a(n): return -(bin(n)[2:].count("1")%2==0)*a065620(n)
print([a(n) for n in range(101)]) # Indranil Ghosh, Jun 07 2017

Formula

a(n) = (1/2) * A010059(n) * A006068(n).
a(n) = -1 * A010059(n) * A065620(n).
a(n) = A246160(n) - A065620(n).
a(n) = A010059(n) * A006068(A245710(n)).
For all n, a(A048724(n)) = n.

A246162 Permutation of natural numbers: a(1) = 1, a(A000069(n)) = A014580(a(n-1)), a(A001969(n)) = A091242(a(n-1)), where A000069 and A001969 are the odious and evil numbers, and A014580 resp. A091242 are the binary coded irreducible resp. reducible polynomials over GF(2).

Original entry on oeis.org

1, 2, 4, 3, 5, 8, 11, 7, 6, 9, 13, 14, 31, 47, 17, 25, 12, 10, 19, 15, 37, 59, 20, 21, 61, 185, 42, 319, 62, 24, 87, 137, 34, 18, 55, 16, 41, 97, 27, 22, 67, 229, 49, 415, 76, 28, 103, 29, 109, 425, 78, 1627, 222, 54, 283, 3053, 373, 79, 433, 33, 131, 647, 108, 1123, 166, 45, 203, 26, 91, 379, 71, 23
Offset: 1

Views

Author

Antti Karttunen, Aug 17 2014. Erroneous comment corrected Aug 20 2014

Keywords

Comments

This is an instance of entanglement-permutation, where the two complementary pairs to be entangled with each other are A000069/A001969 (odious and evil numbers) and A014580/A091242 (binary codes for irreducible and reducible polynomials over GF(2)).
Because 3 is the only evil number in A014580, it implies that, apart from a(4)=3, all other odious positions contain an odious number. There are also odious numbers in some of the evil positions, precisely all the terms of A246158 in some order, together with all evil numbers larger than 3. (Permutation A246164 has the same property, except there a(7)=3.) See comments in A246161 for more details how this affects the cycle structure of these permutations.

Links

Crossrefs

Inverse: A246161.
Related permutations: A006068, A233279, A234612, A237427, A245702, A246202, A246164.
Cf. A010060, A014580, A091242, A115384, A245710.

Formula

a(1) = 1, and for n > 1, if A010060(n) = 1 [i.e. n is one of the odious numbers, A000069], a(n) = A014580(a(A115384(n)-1)), otherwise, a(n) = A091242(a(A245710(n))).
As a composition of related permutations:
a(n) = A245702(A233279(n)).
a(n) = A246202(A006068(n)).
a(n) = A246164(A234612(n)).
For all n > 1, A091225(a(n)) = A010060(n). [Maps odious numbers to binary representations of irreducible GF(2) polynomials (A014580) and evil numbers to the corresponding representations of reducible polynomials (A091242), in some order].

A277808 a(n) = number of iterations of map k -> A003188(A006068(k)/2) that are required (when starting from k = n) until k is an odious number.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Nov 03 2016

Keywords

Links

Crossrefs

One less than A277822.
A left inverse of A003945.
Cf. A277812 (gives the odious number where such an iteration is finished at when starting from k=n).
Cf. A000069, A001969, A001511, A003188, A006068, A010059, A010060, A245710, A268389.

Formula

a(n) = A010059(n) * A001511(n).
If A010060(n) = 1 [when n is one of the odious numbers, A000069], then a(n) = 0, otherwise a(n) = 1 + a(A003188(A006068(n)/2)).
Other identities:
For all n >= 0, a(A003945(n)) = n.

A276444 Permutation of natural numbers: a(1) = 1; a(A001969(1+n)) = A088359(a(n)), a(A000069(1+n)) = A087686(1+a(n)), where A088359 & A087686 = numbers that occur only once & more than once in A004001, and A000069 & A001969 are odious & evil numbers.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 11, 14, 15, 13, 16, 17, 18, 21, 19, 24, 27, 22, 20, 26, 30, 25, 31, 28, 23, 29, 32, 33, 34, 38, 35, 42, 48, 39, 36, 45, 54, 43, 58, 49, 40, 51, 37, 47, 57, 46, 62, 55, 44, 56, 63, 59, 50, 60, 41, 53, 61, 52, 64, 65, 66, 71, 67, 76, 86, 72, 68, 80, 96, 77, 106, 87, 73, 90, 69, 83, 102, 81
Offset: 1

Views

Author

Antti Karttunen, Sep 03 2016

Keywords

Links

Crossrefs

Inverse: A276443.
Cf. A000069, A001969, A004001, A010060, A087686, A088359, A115384, A245710.
Similar or related permutations: A006068, A276442, A276446.

Programs

Formula

a(1) = 1, and for n > 1, if A010060(n) = 0 [when n is one of the evil numbers, A001969], a(n) = A088359(a(A245710(n))), otherwise a(n) = A087686(1+a(A115384(n)-1)).
As a composition of other permutations:
a(n) = A276442(A006068(n)).

A276446 Permutation of natural numbers: a(1) = 1; a(A000069(1+n)) = A088359(a(n)), a(A001969(1+n)) = A087686(1+a(n)), where A088359 & A087686 = numbers that occur only once & more than once in A004001, and A000069 & A001969 are odious & evil numbers.

Original entry on oeis.org

1, 3, 2, 6, 7, 4, 5, 11, 14, 15, 13, 8, 9, 10, 12, 20, 26, 30, 25, 31, 28, 23, 29, 16, 17, 18, 21, 19, 24, 27, 22, 37, 47, 57, 46, 62, 55, 44, 56, 63, 59, 50, 60, 41, 53, 61, 52, 32, 33, 34, 38, 35, 42, 48, 39, 36, 45, 54, 43, 58, 49, 40, 51, 70, 85, 105, 84, 120, 103, 82, 104, 126, 117, 98, 118, 79, 101, 119, 100, 127, 122, 108, 123, 89
Offset: 1

Views

Author

Antti Karttunen, Sep 03 2016

Keywords

Links

Crossrefs

Inverse: A276445.
Cf. A000069, A001969, A004001, A010060, A087686, A088359, A115384, A245710.
Similar or related permutations: A006068, A267112, A276444.

Programs

Formula

a(1) = 1, and for n > 1, if A010060(n) = 1 [when n is one of the odious numbers, A000069], a(n) = A088359(a(A115384(n)-1)), otherwise a(n) = A087686(1+a(A245710(n))).
As a composition of other permutations:
a(n) = A267112(A006068(n)).

A269855 a(0) = 1, a(1) = 2, after which, a(nth_odious_number_larger_than_one(n)) = A250469(a(n)), a(nth_evil_number_larger_than_zero(n)) = 2*a(n).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 8, 9, 7, 10, 12, 15, 16, 21, 25, 18, 11, 14, 20, 27, 24, 33, 35, 30, 32, 45, 55, 42, 49, 50, 36, 51, 13, 22, 28, 39, 40, 57, 65, 54, 48, 69, 85, 66, 77, 70, 60, 87, 64, 93, 115, 90, 91, 110, 84, 123, 121, 98, 100, 147, 72, 105, 125, 102, 17, 26, 44, 63, 56, 81, 95, 78, 80, 117, 145, 114, 119, 130, 108, 159, 96
Offset: 0

Views

Author

Antti Karttunen, Mar 07 2016

Keywords

Comments

Permutation of natural numbers obtained from the sieve of Eratosthenes, combined with the inverse of Gray code. Note the indexing: Domain starts from 0, range from 1.

Links

Crossrefs

Inverse: A269856.
Cf. A000069, A001969, A010060, A115384, A245710, A250469.
Related or similar permutations: A006068, A252755, A269851.

Formula

a(0) = 1, a(1) = 2, for n > 1, if A010060(n) = 1 [when n is one of the odious numbers A000069], a(n) = A250469(a(A115384(n)-1)), otherwise [when n is one of the evil numbers A001969], a(n) = 2*a(A245710(n)).
As a composition of other permutations:
a(n) = A252755(A006068(n)).
Showing 1-7 of 7 results.

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