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.

A296085 Filter sequence combining A296078(n) and A296092(n), the prime signatures of 1+phi(n) and 1+sigma(n).

Original entry on oeis.org

1, 2, 1, 3, 1, 1, 2, 4, 5, 1, 1, 1, 5, 2, 6, 7, 1, 8, 5, 9, 5, 1, 2, 9, 10, 1, 1, 5, 1, 9, 5, 11, 12, 5, 6, 13, 5, 1, 14, 5, 1, 1, 13, 15, 9, 1, 2, 3, 5, 15, 16, 17, 5, 2, 1, 6, 4, 5, 1, 2, 13, 1, 18, 19, 14, 15, 5, 16, 20, 14, 1, 21, 13, 5, 3, 5, 1, 6, 4, 15, 15, 1, 5, 21, 16, 5, 12, 1, 5, 14, 1, 22, 5, 5, 2, 15, 13, 13, 1, 5, 1, 15, 18, 9, 9
Offset: 1

Views

Author

Antti Karttunen, Dec 08 2017

Keywords

Comments

Restricted growth sequence transform of P(A296078(n), A296092(n)), where P(a,b) is a two-argument form of A000027 used as a Cantor pairing function N x N -> N.
For all i, j:
a(i) = a(j) => A296213(i) = A296213(j).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ This function from Charles R Greathouse IV, Aug 17 2011
    A296078(n) = A046523(1+eulerphi(n));
    A296092(n) = A046523(1+sigma(n));
    Anotsubmitted5(n) = (1/2)*(2 + ((A296078(n)+A296092(n))^2) - A296078(n) - 3*A296092(n));
    write_to_bfile(1,rgs_transform(vector(up_to,n,Anotsubmitted5(n))),"b296085.txt");

A300224 Filter sequence combining A046523(n) and A296078(n), prime signature of n and prime signature of phi(n)+1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 4, 2, 6, 2, 4, 7, 8, 2, 6, 2, 9, 4, 4, 2, 10, 11, 4, 5, 6, 2, 12, 2, 13, 14, 4, 7, 15, 2, 4, 7, 16, 2, 17, 2, 18, 9, 4, 2, 19, 3, 18, 14, 9, 2, 16, 4, 10, 4, 4, 2, 20, 2, 4, 6, 21, 7, 22, 2, 18, 23, 12, 2, 24, 2, 4, 6, 6, 4, 12, 2, 25, 26, 4, 2, 27, 14, 4, 14, 16, 2, 27, 4, 28, 4, 4, 4, 29, 2, 6, 6, 15, 2, 22, 2, 10, 12
Offset: 1

Views

Author

Antti Karttunen, Mar 01 2018

Keywords

Comments

Restricted growth sequence transform of P(A046523(n), A296078(n)), where P(a,b) is a two-argument form of A000027 used as a Cantor pairing function N x N -> N.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ This function from Charles R Greathouse IV, Aug 17 2011
    A296078(n) = A046523(1+eulerphi(n));
    Aux300224(n) = (1/2)*(2 + ((A296078(n)+A046523(n))^2) - A296078(n) - 3*A046523(n));
    write_to_bfile(1,rgs_transform(vector(up_to,n,Aux300224(n))),"b300224.txt");

A300225 Filter sequence combining A296078(n) and A296091(n), the prime signatures of phi(n)+1 and sigma(n)-1, with a(1) = 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 2, 2, 3, 4, 2, 2, 5, 2, 2, 6, 7, 2, 3, 2, 6, 2, 3, 2, 6, 8, 2, 3, 3, 2, 6, 2, 3, 9, 2, 6, 10, 2, 2, 11, 2, 2, 3, 2, 9, 11, 2, 2, 3, 12, 13, 9, 6, 2, 3, 2, 11, 2, 2, 2, 2, 2, 3, 2, 14, 6, 15, 2, 16, 17, 11, 2, 11, 2, 2, 3, 2, 3, 6, 2, 15, 18, 5, 2, 6, 9, 2, 15, 2, 2, 6, 3, 19, 2, 3, 3, 9, 2, 20, 3, 21, 2, 15, 2, 11, 6
Offset: 1

Views

Author

Antti Karttunen, Mar 01 2018

Keywords

Comments

Restricted growth sequence transform of P(A296078(n), A296091(n)), where P(a,b) is a two-argument form of A000027 used as a Cantor pairing function N x N -> N.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ This function from Charles R Greathouse IV, Aug 17 2011
    A296078(n) = A046523(1+eulerphi(n));
    A296091(n) = if(1==n,n,A046523(sigma(n)-1);)
    Aux300225(n) = (1/2)*(2 + ((A296078(n)+A296091(n))^2) - A296078(n) - 3*A296091(n));
    write_to_bfile(1,rgs_transform(vector(up_to,n,Aux300225(n))),"b300225.txt");

A296079 a(n) = 1 if 1+phi(n) is prime, 0 otherwise, where phi = A000010, Euler totient function.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0
Offset: 1

Views

Author

Antti Karttunen, Dec 05 2017

Keywords

Comments

Out of the first 65537 values, 26197 are 1's (indicating primes), and 39340 are 0's, indicating nonprimes.

Crossrefs

Characteristic function of A039698.
Cf. A039689 (positions of zeros).
Cf. also A296077, A296078, A296080.

Programs

  • Mathematica
    Table[If[PrimeQ[EulerPhi[n]+1],1,0],{n,120}] (* Harvey P. Dale, Apr 23 2020 *)
  • PARI
    A296079(n) = isprime(1+eulerphi(n));

Formula

a(n) = A010051(A039649(n)) = A010051(1+A000010(n)).
For all n, a(n) >= A010051(n) and a(2n) >= A010051(n).

A296076 Least number with the same prime signature as 1 + A002322(n), where A002322 is Carmichael's lambda.

Original entry on oeis.org

2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 12, 2, 2, 2, 4, 2
Offset: 1

Views

Author

Antti Karttunen, Dec 05 2017

Keywords

Crossrefs

Cf. A002322, A046523, A263027, A263028 (positions of 2's), A296077, A296078.

Programs

Formula

a(n) = A046523(A263027(n)) = A046523(1+A002322(n)).

A296092 Least number with the same prime signature as sigma(n)+1.

Original entry on oeis.org

2, 4, 2, 8, 2, 2, 4, 16, 6, 2, 2, 2, 6, 4, 4, 32, 2, 24, 6, 2, 6, 2, 4, 2, 32, 2, 2, 6, 2, 2, 6, 64, 4, 6, 4, 12, 6, 2, 6, 6, 2, 2, 12, 6, 2, 2, 4, 8, 6, 6, 2, 12, 6, 4, 2, 4, 16, 6, 2, 4, 12, 2, 30, 128, 6, 6, 6, 2, 2, 6, 2, 36, 12, 6, 8, 6, 2, 4, 16, 6, 6, 2, 6, 36, 2, 6, 4, 2, 6, 6, 2, 4, 6, 6, 4, 6, 12, 12, 2, 6, 2, 6, 30, 2, 2
Offset: 1

Views

Author

Antti Karttunen, Dec 07 2017

Keywords

Crossrefs

Programs

Formula

a(n) = A046523(A088580(n)) = A046523(1+A000203(n)).

A296080 Restricted growth sequence transform of A289625(1+phi(n)), where phi = A000010, Euler totient function.

Original entry on oeis.org

1, 1, 2, 2, 3, 2, 4, 3, 4, 3, 5, 3, 6, 4, 4, 4, 7, 4, 8, 4, 6, 5, 9, 4, 10, 6, 8, 6, 11, 4, 12, 7, 10, 7, 13, 6, 14, 8, 13, 7, 15, 6, 16, 10, 13, 9, 17, 7, 16, 10, 18, 13, 19, 8, 15, 13, 14, 11, 20, 7, 21, 12, 14, 18, 16, 10, 22, 18, 23, 13, 24, 13, 25, 14, 15, 14, 21, 13, 26, 18, 27, 15, 28, 13, 29, 16, 30, 15, 31, 13, 25, 23, 21, 17, 25, 18, 32, 16, 21, 15
Offset: 1

Views

Author

Antti Karttunen, Dec 05 2017

Keywords

Crossrefs

Programs

  • PARI
    allocatemem(2^30);
    up_to = 65537;
    rgs_transform(invec) = { my(occurrences = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(occurrences,invec[i]), my(pp = mapget(occurrences, invec[i])); outvec[i] = outvec[pp] , mapput(occurrences,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A289625(n) = { my(m=1,p=2,v=znstar(n)[2]); for(i=1,length(v),m *= p^v[i]; p = nextprime(p+1)); (m); };
    write_to_bfile(1,rgs_transform(vector(up_to,n,A289625(1+eulerphi(n)))),"b296080.txt");
Showing 1-7 of 7 results.