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 1-5 of 5 results.

A366275 The Cat's tongue permutation: a(n) = A163511(A057889(n)).

Original entry on oeis.org

1, 2, 4, 3, 8, 9, 6, 5, 16, 27, 18, 15, 12, 25, 10, 7, 32, 81, 54, 45, 36, 75, 30, 21, 24, 125, 50, 35, 20, 49, 14, 11, 64, 243, 162, 135, 108, 225, 90, 63, 72, 375, 150, 105, 60, 147, 42, 33, 48, 625, 250, 175, 100, 245, 70, 55, 40, 343, 98, 77, 28, 121, 22, 13, 128, 729, 486, 405, 324, 675, 270, 189, 216, 1125
Offset: 0

Views

Author

Antti Karttunen, Oct 06 2023

Keywords

Comments

"Cat's tongue" refers to the look of the scatter plot of this sequence.

Crossrefs

Cf. A000040, A000225, A007814, A057889, A163511, A209229, A290251, A366276 (inverse map), A366277 (fixed points of map n -> a(n)), A366278, A366279, A366280, A366281 [= A052409(a(n))], A366282 [= a(n)-n], A366283 [= gcd(n,a(n))].
Cf. also A163511, A253563, A366263 (compare the scatter plots).

Programs

  • PARI
    A030101(n) = if(n<1,0,subst(Polrev(binary(n)),x,2));
    A057889(n) = if(!n,n,A030101(n/(2^valuation(n,2))) * (2^valuation(n, 2)));
    A163511(n) = if(!n, 1, my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(1+p)); n >>= 1); (t*p));
    A366275(n) = A163511(A057889(n));
    
  • Python
    from sympy import prime
    def A366275(n):
        if n:
            k, c, m = int(bin(n>>(r:=(~n & n-1).bit_length()))[:1:-1],2)<>= s+1
            return m*prime(c)
        return 1 # Chai Wah Wu, Oct 08 2023

Formula

For n >= 0, A001222(a(n)) = A290251(n).
For n >= 1, A007814(a(n)) = A135523(n) = A007814(n) + A209229(n). [Like A163511, also this permutation preserves the 2-adic valuation of n, except when n is a power of two, in which cases that value is incremented by one.]
For n >= 1, a(2*n) = 2*a(n).
For n >= 1, a(A000225(n)) = A000040(n).

A366283 a(n) = gcd(n, A366275(n)), where A366275 is the Cat's tongue permutation.

Original entry on oeis.org

1, 1, 2, 3, 4, 1, 6, 1, 8, 9, 2, 1, 12, 1, 2, 1, 16, 1, 18, 1, 4, 3, 2, 1, 24, 25, 2, 1, 4, 1, 2, 1, 32, 3, 2, 5, 36, 1, 2, 3, 8, 1, 6, 1, 4, 3, 2, 1, 48, 1, 50, 1, 4, 1, 2, 55, 8, 1, 2, 1, 4, 1, 2, 1, 64, 1, 6, 1, 4, 3, 10, 1, 72, 1, 2, 15, 4, 7, 6, 1, 16, 3, 2, 1, 12, 5, 2, 3, 8, 1, 6, 7, 4, 3, 2, 1, 96, 1, 2, 1, 100
Offset: 0

Views

Author

Antti Karttunen, Oct 07 2023

Keywords

Crossrefs

Differs from related A364255 for the first time at n=25, where a(25) = 25, while A364255(25) = 5.

Programs

Formula

a(n) = gcd(n,A366282(n)) = gcd(A366275(n),A366282(n)).
a(n) = n / A366284(n) = A366275(n) / A366285(n).

A366285 a(n) = A366275(n) / gcd(n, A366275(n)), where A366275 is the Cat's tongue permutation.

Original entry on oeis.org

1, 2, 2, 1, 2, 9, 1, 5, 2, 3, 9, 15, 1, 25, 5, 7, 2, 81, 3, 45, 9, 25, 15, 21, 1, 5, 25, 35, 5, 49, 7, 11, 2, 81, 81, 27, 3, 225, 45, 21, 9, 375, 25, 105, 15, 49, 21, 33, 1, 625, 5, 175, 25, 245, 35, 1, 5, 343, 49, 77, 7, 121, 11, 13, 2, 729, 81, 405, 81, 225, 27, 189, 3, 1125, 225, 21, 45, 63, 21, 99, 9, 625, 375, 525
Offset: 0

Views

Author

Antti Karttunen, Oct 07 2023

Keywords

Comments

Denominator of n / A366275(n).

Crossrefs

Cf. A057889, A163511, A366275, A366282, A366283, A366284 (numerators), A366286 (rgs-transform).
Cf. also A364492.

Programs

Formula

a(n) = A366275(n) / A366283(n) = A366275(n) / gcd(n, A366275(n))

A366372 a(n) = A332214(n) - n, where A332214 is the Mersenne-prime fixing variant of permutation A163511.

Original entry on oeis.org

1, 1, 2, 0, 4, 4, 0, 0, 8, 18, 8, 38, 0, 8, 0, -10, 16, 64, 36, 324, 16, 126, 76, 2, 0, 38, 16, 8, 0, -14, -20, 0, 32, 210, 128, 2366, 72, 992, 648, 86, 32, 400, 252, 132, 152, 30, 4, 914, 0, 140, 76, 194, 32, 52, 16, 100, 0, -12, -28, 158, -40, 32, 0, -52, 64, 664, 420, 16740, 256, 7134, 4732, 554, 144, 3014, 1984
Offset: 0

Views

Author

Antti Karttunen, Oct 08 2023

Keywords

Crossrefs

Cf. A332214, A335431 (known positions of 0's), A366373, A366374, A366375, A366376.
Cf. also A364253, A364258, A366282.

Programs

A366284 a(n) = n / gcd(n, A366275(n)), where A366275 is the Cat's tongue permutation.

Original entry on oeis.org

0, 1, 1, 1, 1, 5, 1, 7, 1, 1, 5, 11, 1, 13, 7, 15, 1, 17, 1, 19, 5, 7, 11, 23, 1, 1, 13, 27, 7, 29, 15, 31, 1, 11, 17, 7, 1, 37, 19, 13, 5, 41, 7, 43, 11, 15, 23, 47, 1, 49, 1, 51, 13, 53, 27, 1, 7, 57, 29, 59, 15, 61, 31, 63, 1, 65, 11, 67, 17, 23, 7, 71, 1, 73, 37, 5, 19, 11, 13, 79, 5, 27, 41, 83, 7, 17, 43, 29, 11
Offset: 0

Views

Author

Antti Karttunen, Oct 07 2023

Keywords

Comments

Numerator of n / A366275(n).

Crossrefs

Cf. also A364491.

Programs

Formula

a(n) = n / A366283(n) = n / gcd(n, A366275(n))
Showing 1-5 of 5 results.