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.

A065204 Least m such that A065203(m) = n.

Original entry on oeis.org

1, 3, 22, 191, 2206, 29054, 497585
Offset: 1

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Author

Vladeta Jovovic, Oct 21 2001

Keywords

Comments

Conjecture: A064413(a(n)) = A002110(n) (primorial numbers), i.e., a(n) sets positions of primorial numbers in A064413.

Crossrefs

Extensions

a(6)-a(7) from Sean A. Irvine, Aug 21 2023

A278263 Least number with the same prime signature as the n-th term of EKG-sequence: a(n) = A046523(A064413(n)).

Original entry on oeis.org

1, 2, 4, 6, 2, 4, 12, 8, 6, 2, 6, 12, 6, 2, 6, 24, 16, 12, 6, 2, 6, 8, 30, 4, 6, 12, 6, 2, 6, 36, 32, 6, 2, 6, 30, 6, 2, 6, 12, 24, 12, 6, 2, 6, 48, 12, 12, 24, 24, 4, 12, 60, 6, 6, 30, 6, 2, 6, 30, 6, 2, 6, 72, 64, 12, 6, 2, 6, 12, 30, 12, 48, 6, 2, 6, 16, 60, 6, 24, 6, 2, 6, 60, 6, 6, 36, 12, 6, 2, 6, 96, 12, 6, 24, 30, 12, 30, 72, 6, 2, 6, 30, 30, 48, 12, 6
Offset: 1

Views

Author

Antti Karttunen, Nov 16 2016

Keywords

Comments

This sequence works as a "sentinel" for EKG-sequence by matching to any sequence that is obtained as f(A064413(n)), where f(n) is any function that depends only on the prime signature of n (see the index entry for "sequences computed from exponents in ..."). The last line in Crossrefs section lists such sequences that were present in the database as of Nov 11 2016.
Terms and b-file computed from b-file of A064413 provided by Zak Seidov.

Crossrefs

Sequences that partition N into same or coarser equivalence classes: A064742, A065203.

Programs

Formula

a(n) = A046523(A064413(n)).

A304113 Restricted growth sequence transform of A278263(n) = A046523(A064413(n)), a filter based on the prime signature of EKG-sequence.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, May 17 2018

Keywords

Comments

For all i, j: a(i) = a(j) => A064742(i) = A064742(j).
For all i, j: a(i) = a(j) => A065203(i) = A065203(j).

Crossrefs

Programs

  • PARI
    \\ Needs also code for A064413:
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    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
    A278263(n) = A046523(A064413(n));
    write_to_bfile(1,rgs_transform(vector(65539,n,A278263(n))),"b304113.txt");
Showing 1-3 of 3 results.