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.

A305982 a(n) = Product_{d|n, dA305793(1+d)-1), where A305973(k) records the prime signature of 2k-1.

Original entry on oeis.org

1, 2, 2, 4, 2, 8, 2, 12, 4, 8, 2, 48, 2, 20, 8, 24, 2, 32, 2, 120, 20, 8, 2, 288, 4, 28, 8, 120, 2, 320, 2, 120, 8, 20, 20, 576, 2, 20, 28, 480, 2, 320, 2, 264, 32, 8, 2, 4320, 10, 200, 20, 168, 2, 320, 8, 1200, 20, 8, 2, 11520, 2, 44, 80, 600, 28, 704, 2, 300, 8, 800, 2, 6912, 2, 44, 80, 300, 20, 448, 2, 31200, 40, 8, 2, 72000, 20, 20, 8
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Crossrefs

Cf. A305973, A305983 (rgs-transform), A305984.

Programs

  • PARI
    A305982(n) = { my(m=1); fordiv(n, d, if((dA305973(1+d)-1))); (m); }; \\ Needs also code from A305973.

Formula

a(n) = Product_{d|n, dA008578(A305793(1+d)).

A305984 a(n) = Product_{d|n, d>1} prime(A305793(1+d)-1), where A305973(k) records the prime signature of 2k-1.

Original entry on oeis.org

1, 2, 2, 6, 2, 8, 5, 12, 4, 20, 2, 72, 7, 20, 8, 60, 5, 32, 5, 120, 20, 44, 2, 432, 10, 28, 20, 300, 2, 320, 11, 300, 8, 50, 20, 576, 11, 50, 28, 3120, 2, 800, 5, 264, 80, 20, 5, 4320, 55, 200, 20, 1428, 2, 320, 20, 1200, 50, 44, 5, 17280, 5, 154, 80, 1500, 28, 1760, 19, 300, 8, 2000, 5, 17280, 11, 44, 80, 1650, 50, 448, 5, 78000, 40, 68, 2
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Crossrefs

Cf. A305973, A305982, A305985 (rgs-transform).

Programs

  • PARI
    A305984(n) = { my(m=1); fordiv(n, d, if((d>1), m *= prime(A305973(1+d)-1))); (m); }; \\ Needs also code from A305973.

Formula

a(n) = Product_{d|n, d>1} A008578(A305793(1+d)).

A305985 Filter sequence combining from all divisors d > 1 of n, the prime signature of 2d+1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 5, 6, 7, 8, 2, 9, 10, 8, 4, 11, 5, 12, 5, 13, 8, 14, 2, 15, 16, 17, 8, 18, 2, 19, 20, 18, 4, 21, 8, 22, 20, 21, 17, 23, 2, 24, 5, 25, 26, 8, 5, 27, 28, 29, 8, 30, 2, 19, 8, 31, 21, 14, 5, 32, 5, 33, 26, 34, 17, 35, 36, 18, 4, 37, 5, 32, 20, 14, 26, 38, 21, 39, 5, 40, 41, 42, 2, 43, 44, 8, 14, 45, 2, 46, 47, 18, 44, 48, 8, 49, 50, 51, 12, 52, 5
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Comments

Restricted growth sequence transform of A305984.
For all i, j: a(i) = a(j) => A086668(i) = A086668(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; };
    A305984(n) = { my(m=1); fordiv(n, d, if((d>1), m *= prime(A305973(1+d)-1))); (m); }; \\ Needs also code from A305973.
    v305985 = rgs_transform(vector(up_to,n,A305984(n)));
    A305985(n) = v305985[n];

A305978 Filter sequence combining prime signatures of n and 2n+1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 5, 6, 7, 8, 2, 9, 10, 4, 4, 11, 5, 12, 5, 12, 4, 13, 2, 14, 15, 4, 16, 17, 2, 18, 19, 20, 4, 8, 4, 21, 19, 8, 4, 22, 2, 23, 5, 12, 17, 8, 5, 24, 25, 12, 4, 26, 2, 27, 8, 27, 8, 13, 5, 28, 5, 29, 12, 30, 4, 23, 31, 12, 4, 23, 5, 32, 19, 4, 12, 33, 8, 18, 5, 34, 35, 36, 2, 28, 13, 4, 13, 37, 2, 38, 8, 17, 8, 39, 4, 40, 41, 12, 12, 42, 5, 23
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Comments

Restricted growth sequence transform of A286258.

Crossrefs

Cf. A005384 (positions of 2's), A234095 (of 5's).

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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    Aux305978(n) = [A046523(n),A046523(n+n+1)];
    v305978 = rgs_transform(vector(up_to,n,Aux305978(n)));
    A305978(n) = v305978[n];

A305983 Filter sequence combining from all proper divisors d of n, the prime signature of 2d+1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 4, 2, 6, 2, 7, 4, 8, 2, 9, 2, 10, 7, 4, 2, 11, 3, 12, 4, 10, 2, 13, 2, 10, 4, 7, 7, 14, 2, 7, 12, 15, 2, 13, 2, 16, 9, 4, 2, 17, 18, 19, 7, 20, 2, 13, 4, 21, 7, 4, 2, 22, 2, 23, 24, 25, 12, 26, 2, 27, 4, 28, 2, 29, 2, 23, 24, 27, 7, 30, 2, 31, 32, 4, 2, 33, 7, 7, 4, 34, 2, 35, 36, 10, 23, 7, 7, 37, 2, 38, 9, 39, 2, 28, 2, 40, 13
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Comments

Restricted growth sequence transform of A305982.
For all i, j: a(i) = a(j) => A305818(i) = A305818(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; };
    A305982(n) = { my(m=1); fordiv(n, d, if((dA305973(1+d)-1))); (m); }; \\ Needs also code from A305973.
    v305983 = rgs_transform(vector(up_to,n,A305982(n)));
    A305983(n) = v305983[n];

A305977 Filter sequence combining prime signatures of n and 2n-1.

Original entry on oeis.org

1, 2, 2, 3, 4, 5, 2, 6, 3, 5, 7, 8, 4, 9, 5, 10, 7, 11, 2, 11, 5, 5, 12, 13, 14, 15, 16, 11, 7, 17, 2, 18, 15, 5, 15, 19, 2, 20, 15, 13, 21, 17, 7, 11, 8, 15, 7, 22, 3, 23, 5, 8, 24, 13, 5, 25, 5, 15, 12, 26, 4, 15, 27, 28, 15, 17, 7, 29, 5, 17, 7, 30, 7, 20, 8, 8, 20, 31, 2, 22, 32, 5, 24, 33, 34, 20, 5, 35, 7, 33, 5, 11, 15, 15, 36, 37, 2, 38, 8, 19, 7, 31
Offset: 1

Views

Author

Antti Karttunen, Jun 15 2018

Keywords

Comments

Restricted growth sequence transform of A286257.

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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    Aux305977(n) = [A046523(n),A046523(n+n-1)];
    v305977 = rgs_transform(vector(up_to,n,Aux305977(n)));
    A305977(n) = v305977[n];
Showing 1-6 of 6 results.