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.

A320115 Filter sequence for counting the residue classes mod 4 of divisors of n.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Oct 06 2018

Keywords

Comments

Restricted growth sequence transform of A320114.
For all i, j:
A319994(i) = A319994(j) => a(i) = a(j),
A320004(i) = A320004(j) => a(i) = a(j),
a(i) = a(j) => A002654(i) = A002654(j).

Crossrefs

Programs

  • PARI
    up_to = 100000;
    A320114(n) = { my(m=1); fordiv(n,d,if(d>1, m *= prime(1+(d%4)))); (m); };
    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; };
    v320115 = rgs_transform(vector(up_to,n,A320114(n)));
    A320115(n) = v320115[n];

A320116 a(n) = Product_{d|n, d>1} prime(1+(d mod 6)).

Original entry on oeis.org

1, 5, 7, 55, 13, 70, 3, 275, 49, 715, 13, 1540, 3, 75, 637, 3025, 13, 980, 3, 39325, 147, 715, 13, 15400, 39, 75, 343, 9075, 13, 140140, 3, 15125, 637, 715, 507, 43120, 3, 75, 147, 2162875, 13, 14700, 3, 39325, 31213, 715, 13, 338800, 9, 10725, 637, 9075, 13, 13720, 507, 226875, 147, 715, 13, 30830800, 3, 75, 7203, 166375, 507, 140140, 3
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2018

Keywords

Crossrefs

Cf. A320114, A320117 (rgs-transform),
Cf. also A319986.

Programs

  • PARI
    A320116(n) = { my(m=1); fordiv(n,d,if(d>1, m *= prime(1+(d%6)))); (m); };

Formula

a(n) = Product_{d|n, d>1} prime(1+(d mod 6)).

A319984 Fully multiplicative with a(p^e) = prime(p mod 4)^e.

Original entry on oeis.org

1, 3, 5, 9, 2, 15, 5, 27, 25, 6, 5, 45, 2, 15, 10, 81, 2, 75, 5, 18, 25, 15, 5, 135, 4, 6, 125, 45, 2, 30, 5, 243, 25, 6, 10, 225, 2, 15, 10, 54, 2, 75, 5, 45, 50, 15, 5, 405, 25, 12, 10, 18, 2, 375, 10, 135, 25, 6, 5, 90, 2, 15, 125, 729, 4, 75, 5, 18, 25, 30, 5, 675, 2, 6, 20, 45, 25, 30, 5, 162, 625, 6, 5, 225, 4, 15, 10, 135, 2, 150, 10, 45, 25, 15, 10
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2018

Keywords

Comments

For all i, j:
A319714(i) = A319714(j) => a(i) = a(j) => A065338(i) = A065338(j).

Crossrefs

Programs

  • PARI
    A319984(n) = { my(f=factor(n)); prod(i=1, #f~, (prime(f[i, 1]%4))^f[i, 2]); };

Formula

For all n, A003963(a(n)) = A065338(n).

A320108 a(n) = Product_{d|n, d>1} prime(1+(d mod 8)).

Original entry on oeis.org

1, 5, 7, 55, 13, 595, 19, 110, 21, 325, 7, 71995, 13, 1615, 1729, 220, 3, 8925, 7, 39325, 1729, 595, 19, 287980, 39, 325, 147, 195415, 13, 12492025, 19, 440, 147, 75, 1729, 11879175, 13, 595, 1729, 157300, 3, 12492025, 7, 71995, 67431, 1615, 19, 1151920, 57, 4875, 147, 39325, 13, 1062075, 1729, 781660, 147, 325, 7, 182895738025, 13, 1615, 98553, 880, 507
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2018

Keywords

Crossrefs

Cf. A320109 (rgs-transform).

Programs

  • PARI
    A320108(n) = { my(m=1); fordiv(n,d,if(d>1, m *= prime(1+(d%8)))); (m); };

Formula

a(n) = Product_{d|n, d>1} prime(1+(d mod 8)).

A320112 a(n) = Product_{d|n, d>1} prime(1+(d mod 12)).

Original entry on oeis.org

1, 5, 7, 55, 13, 595, 19, 1265, 203, 2015, 37, 13090, 3, 475, 637, 13915, 13, 293335, 19, 509795, 3857, 5735, 37, 602140, 39, 75, 1421, 57475, 13, 28534415, 19, 320045, 7511, 2015, 9139, 12906740, 3, 475, 147, 128978135, 13, 27866825, 19, 1450955, 535717, 5735, 37, 13247080, 57, 30225, 637, 9075, 13, 34906865, 9139, 30404275, 3857, 2015, 37
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2018

Keywords

Crossrefs

Cf. A320113 (rgs-transform).

Programs

  • PARI
    A320112(n) = { my(m=1); fordiv(n,d,if(d>1, m *= prime(1+(d%12)))); (m); };

Formula

a(n) = Product_{d|n, d>1} prime(1+(d mod 12)).
Showing 1-5 of 5 results.