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 1-3 of 3 results.

A318838 Product_{d|n, A007431(d) > 0} prime(A007431(d)), where A007431 is the Möbius transform of Euler's totient function.

Original entry on oeis.org

2, 2, 4, 4, 10, 4, 22, 12, 28, 10, 46, 16, 62, 22, 100, 84, 94, 28, 118, 100, 484, 46, 146, 144, 530, 62, 1036, 484, 206, 100, 218, 1596, 2116, 94, 5170, 784, 298, 118, 3844, 3900, 334, 484, 358, 2116, 25900, 146, 394, 7056, 3322, 530, 8836, 3844, 466, 1036, 23690, 42108, 13924, 206, 538, 10000, 554, 218, 240548
Offset: 1

Views

Author

Antti Karttunen, Sep 05 2018

Keywords

Crossrefs

Cf. A000010, A007431, A318839 (rgs-transform).
Cf. also A318836.

Programs

  • PARI
    A007431(n) = sumdiv(n,d,moebius(n/d)*eulerphi(d));
    A318838(n) = { my(m=1); fordiv(n,d,if((A007431(d)!=0),m *= prime(A007431(d)))); (m); };

Formula

a(n) = product_{d|n} A008578(1+A007431(d)).
For all n >= 1, A056239(a(n)) = A000010(n).

A318893 Filter sequence combining the prime signature of n (A046523) with Euler totient function (A000010).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 21, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 34, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 42, 48, 43, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 53, 70, 59, 71, 66, 72, 73, 74, 51, 75, 76, 77, 78, 79, 80, 81, 76, 82, 83, 71
Offset: 1

Views

Author

Antti Karttunen, Sep 16 2018

Keywords

Comments

Restricted growth sequence transform of A286160.
For all i, j: a(i) = a(j) => A062355(i) = A062355(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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    A318893aux(n) = [eulerphi(n), A046523(n)];
    v318893 = rgs_transform(vector(up_to,n,A318893aux(n)));
    A318893(n) = v318893[n];

A318892 Filter sequence combining the prime signature of n (A046523) with A289625.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 35, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 44, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 68, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 75, 90
Offset: 1

Views

Author

Antti Karttunen, Sep 16 2018

Keywords

Comments

Restricted growth sequence transform of A289628.
For all i, j: a(i) = a(j) => A318893(i) = A318893(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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    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); };
    A318892aux(n) = [A046523(n), A289625(n)];
    v318892 = rgs_transform(vector(up_to,n,A318892aux(n)));
    A318892(n) = v318892[n];
Showing 1-3 of 3 results.