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.

A318881 Restricted growth sequence transform of A277906, the least number with same prime signature as phi(n).

Original entry on oeis.org

1, 1, 2, 2, 3, 2, 4, 3, 4, 3, 4, 3, 5, 4, 6, 6, 7, 4, 5, 6, 5, 4, 4, 6, 5, 5, 5, 5, 5, 6, 8, 7, 5, 7, 9, 5, 10, 5, 9, 7, 9, 5, 8, 5, 9, 4, 4, 7, 8, 5, 11, 9, 5, 5, 9, 9, 10, 5, 4, 7, 12, 8, 10, 11, 13, 5, 8, 11, 5, 9, 8, 9, 14, 10, 9, 10, 12, 9, 8, 11, 9, 9, 4, 9, 15, 8, 9, 9, 9, 9, 14, 5, 12, 4, 14, 11, 16, 8, 12, 9, 10, 11, 8, 13, 13
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Links

Crossrefs

Cf. A000010, A046523, A277906, A319342, A319343, A319344, A319345.

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
A277906(n) = A046523(eulerphi(n));
v318881 = rgs_transform(vector(up_to,n,A277906(n)));
A318881(n) = v318881[n];

A319342 a(n) = Product_{d|n, dA318881(d)), where A318881(d) records the prime signature of A000010(d).

Original entry on oeis.org

1, 2, 2, 4, 2, 12, 2, 12, 6, 20, 2, 108, 2, 28, 30, 60, 2, 252, 2, 300, 42, 28, 2, 2700, 10, 44, 42, 588, 2, 11700, 2, 780, 42, 68, 70, 26460, 2, 44, 66, 19500, 2, 19404, 2, 588, 2730, 28, 2, 456300, 14, 1100, 102, 1452, 2, 19404, 70, 32340, 66, 44, 2, 29659500, 2, 76, 3234, 13260, 110, 19404, 2, 3468, 42, 112700, 2, 18918900, 2, 116
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Links

Crossrefs

Cf. A318881, A319343 (rgs-transform), A319344.
Cf. also A305982.

Programs

  • PARI
    A319342(n) = { my(m=1); fordiv(n, d, if((dA318881(d)))); (m); }; \\ Needs also code from A318881

Formula

a(n) = Product_{d|n, dA318881(d)).

A319345 Filter sequence combining the prime signature of phi(d) from all divisors d > 1 of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 7, 11, 12, 13, 14, 15, 16, 17, 12, 18, 19, 13, 7, 20, 21, 22, 19, 23, 12, 24, 25, 26, 19, 27, 28, 29, 30, 22, 31, 32, 33, 34, 25, 23, 35, 13, 7, 36, 37, 38, 39, 40, 12, 34, 28, 41, 42, 22, 7, 43, 44, 45, 46, 47, 48, 34, 25, 49, 19, 50, 25, 51, 52, 53, 54, 55, 56, 57, 25, 58, 59, 60, 7, 61, 62, 45, 31, 41, 33, 63, 64, 23, 65, 13
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Comments

Restricted growth sequence transform of A319344.

Links

Crossrefs

Cf. A318881, A319343, A319344.
Cf. also A305985.

Programs

  • PARI
    up_to = 65537;
A319344(n) = { my(m=1); fordiv(n, d, if((d>1), m *= prime(A318881(d)))); (m); }; \\ Needs also code from A318881
v319345 = rgs_transform(vector(up_to,n,A319344(n)));
A319345(n) = v319345[n];
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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