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 1-6 of 6 results.

A324199 Numbers n such that A324187(n) = 0.

Original entry on oeis.org

0, 6, 60, 98, 108, 928, 930, 946, 1874, 3506, 6688, 7496, 7980, 13640, 14476, 15148, 15956, 27168, 30290, 30292, 32752, 59528, 59986, 60556, 60580, 64338, 65432, 108680, 109732, 119972, 121108, 126280, 126872, 130856, 218276, 229160, 242210, 242306, 438914, 454552, 484420, 484640, 485512, 496904, 507032, 518688, 522848, 523400, 811556, 877636
Offset: 1

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Comments

Sequence A243071(A001599(k)), k >= 1, sorted into ascending order. See also comments in A324185.
Also positions of zeros in A324189.

Crossrefs

Cf. A324200 (subsequence).

Programs

  • PARI
    for(n=0,2^21,if(0==A324187(n),print1(n,", "))); \\ Uses code from A324187.

A324184 a(n) = sigma(A163511(n)).

Original entry on oeis.org

1, 3, 7, 4, 15, 13, 12, 6, 31, 40, 39, 31, 28, 24, 18, 8, 63, 121, 120, 156, 91, 124, 93, 57, 60, 78, 72, 48, 42, 32, 24, 12, 127, 364, 363, 781, 280, 624, 468, 400, 195, 403, 372, 342, 217, 228, 171, 133, 124, 240, 234, 248, 168, 192, 144, 96, 90, 104, 96, 72, 56, 48, 36, 14, 255, 1093, 1092, 3906, 847, 3124, 2343, 2801, 600
Offset: 0

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Crossrefs

Programs

  • PARI
    A324184(n) = if(!n,1,my(p=2,mp=p*p,m=1); while(n>1, if(n%2, p=nextprime(1+p); mp = p*p, if((2==n)||!(n%4),mp *= p,m *= (mp-1)/(p-1))); n >>= 1); (m*(mp-1)/(p-1)));
    
  • PARI
    A163511(n) = if(!n,1,my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(p+1)); n >>= 1); (t*p));
    A324184(n) = sigma(A163511(n));
    
  • Python
    from sympy import nextprime
    def A324184(n):
        if n:
            c, p = 1, 1
            while n:
                c *= ((p:=nextprime(p))**(s:=(~n&n-1).bit_length()+1)-1)//(p-1)
                n >>= s
            return c*(p**(s+1)-1)//(p**s-1)
        return 1 # Chai Wah Wu, Jul 25 2023

Formula

a(n) = A000203(A163511(n)).
For n >= 1, a(n) = A324054(A054429(n)).

A324185 Deficiency of n permuted by A163511: a(n) = A033879(A163511(n)) = 2*A163511(n) - sigma(A163511(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 5, 0, 4, 1, 14, -3, 19, -4, 6, 2, 6, 1, 41, -12, 94, -19, 26, 7, 41, -12, 12, -12, 22, -2, 10, 4, 10, 1, 122, -39, 469, -64, 126, 32, 286, -51, 47, -72, 148, -17, 66, 25, 109, -28, 30, -54, 102, -48, 18, -4, 58, -10, 22, -12, 38, 0, 18, 8, 12, 1, 365, -120, 2344, -199, 626, 157, 2001, -168, 222, -372, 1030, -92, 458, 172, 1198
Offset: 0

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Comments

If there are no odd perfect numbers, then all n for which a(n) is 0 are given by sequence A324200.

Crossrefs

Programs

  • PARI
    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));
    A033879(n) = (2*n-sigma(n));
    A324185(n) = A033879(A163511(n));
    
  • PARI
    A324184(n) = if(!n,1,my(p=2,mp=p*p,m=1); while(n>1, if(n%2, p=nextprime(1+p); mp = p*p, if((2==n)||!(n%4),mp *= p,m *= (mp-1)/(p-1))); n >>= 1); (m*(mp-1)/(p-1)));
    A324185(n) = (2*A163511(n)) - A324184(n);

Formula

a(n) = A033879(A163511(n)) = 2*A163511(n) - A324184(n) = 2*A163511(n) - A000203(A163511(n)).
For n > 0, a(n) = A324055(A054429(n)).

A324051 a(n) = A106315(A156552(n)).

Original entry on oeis.org

0, 1, 2, 5, 4, 2, 6, 0, 1, 18, 10, 3, 16, 4, 12, 67, 12, 4, 18, 30, 36, 260, 22, 16, 8, 8, 44, 5, 20, 1029, 30, 28, 164, 36, 28, 6, 256, 96, 44, 4102, 36, 7, 66, 16, 104, 16391, 46, 12, 13, 32, 130, 8, 28, 51, 70, 480, 942, 65544, 42, 9, 2724, 32, 66, 30, 84, 262153, 124, 508, 40, 10, 4, 1048586, 3320, 20, 188, 50, 52, 11, 78, 24
Offset: 2

Views

Author

Antti Karttunen, Feb 19 2019

Keywords

Comments

Positions of zeros, which is sequence A005940(1+A001599(n)) sorted into ascending order: 2, 9, 125, 325, 351, 4199, ..., has A324201 as its subsequence.

Crossrefs

Programs

Formula

a(n) = A106315(A156552(n)).
a(n) = (A156552(n)*A324105(n)) mod A323243(n).

A324183 a(n) = d(A163511(n)), where d(n) is A000005, the number of divisors of n.

Original entry on oeis.org

1, 2, 3, 2, 4, 3, 4, 2, 5, 4, 6, 3, 6, 4, 4, 2, 6, 5, 8, 4, 9, 6, 6, 3, 8, 6, 8, 4, 6, 4, 4, 2, 7, 6, 10, 5, 12, 8, 8, 4, 12, 9, 12, 6, 9, 6, 6, 3, 10, 8, 12, 6, 12, 8, 8, 4, 8, 6, 8, 4, 6, 4, 4, 2, 8, 7, 12, 6, 15, 10, 10, 5, 16, 12, 16, 8, 12, 8, 8, 4, 15, 12, 18, 9, 18, 12, 12, 6, 12, 9, 12, 6, 9, 6, 6, 3, 12, 10, 16, 8, 18, 12, 12, 6, 16, 12
Offset: 0

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Comments

For all i, j: A286531(i) = A286531(j) => a(i) = a(j).

Crossrefs

Programs

  • PARI
    A324183(n) = if(!n,1,n = ((3<<#binary(n\2))-n-1); my(e=0,m=1); while(n>0, if(!(n%2), m *= (1+e); e=0, e++); n >>= 1); (m*(1+e)));
    
  • PARI
    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));
    A324183(n) = numdiv(A163511(n));
    
  • PARI
    A054429(n) = if(!n,n,((3<<#binary(n\2))-n-1)); \\ After code in A054429
    A106737(n) = sum(k=0, n, (binomial(n+k, n-k)*binomial(n, k)) % 2);
    A324183(n) = A106737(A054429(n));
    
  • Python
    def A324183(n):
        if n:
            c = 1
            while n:
                c *= (s:=(~n&n-1).bit_length()+1)
                n >>= s
            return c*(s+1)//s
        return 1 # Chai Wah Wu, Jul 25 2023

Formula

a(n) = A000005(A163511(n)).
a(n) = A106737(A054429(n)).
For all n >= 0, a(2^n) = n+2.

A324188 a(n) = A324121(A163511(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 12, 2, 1, 4, 3, 1, 4, 12, 2, 2, 3, 1, 24, 4, 1, 2, 3, 3, 12, 6, 24, 4, 6, 4, 8, 2, 1, 2, 3, 1, 8, 24, 4, 4, 3, 1, 12, 6, 1, 6, 3, 1, 4, 120, 18, 2, 24, 24, 16, 4, 10, 2, 48, 4, 56, 12, 4, 2, 1, 1, 12, 6, 1, 2, 1, 1, 24, 12, 48, 40, 12, 8, 16, 4, 1, 20, 3, 3, 4, 36, 6, 14, 15, 3, 36, 6, 21, 2, 3, 3, 36, 6, 720, 8, 6, 4, 24, 6, 120, 12
Offset: 0

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Crossrefs

Programs

  • PARI
    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));
    A324121(n) = gcd(sigma(n),n*numdiv(n));
    A324188(n) = A324121(A163511(n));
    
  • PARI
    A324183(n) = if(!n,1,n = ((3<<#binary(n\2))-n-1); my(e=0,m=1); while(n>0, if(!(n%2), m *= (1+e); e=0, e++); n >>= 1); (m*(1+e)));
    A324184(n) = if(!n,1,my(p=2,mp=p*p,m=1); while(n>1, if(n%2, p=nextprime(1+p); mp = p*p, if((2==n)||!(n%4),mp *= p,m *= (mp-1)/(p-1))); n >>= 1); (m*(mp-1)/(p-1)));
    A324188(n) = gcd(A324184(n), A163511(n)*A324183(n));

Formula

a(n) = A324121(A163511(n)) = gcd(A324184(n), A163511(n)*A324183(n)).
For n > 0, a(n) = A324058(A054429(n)).
Showing 1-6 of 6 results.