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 1-4 of 4 results.

A147800 Minimal value of A007947(m*(5^n-m)) with m coprime to 5.

Original entry on oeis.org

2, 6, 22, 42, 222, 366, 2046, 13962, 10626, 79926, 293262
Offset: 1

Views

Author

M. F. Hasler, Nov 13 2008

Keywords

Comments

The minima are reached for m values given in A147803.
This is related to the abc conjecture.
All terms of this sequence are even, so one could also consider A147800/2 = 1, 3, 11, 21, 111, 183, 1023, 6981, 5313, 39963, 146631, ...

Crossrefs

Cf. A007947, A147803 (m values), A143702 (analog for 2^n), A147801 (analog for 3^n), A147298 (general case).

Programs

  • PARI
    A147800(n, p=5) = {my(m=n=p^n); for(a=1, (n-1)\2, a%p || next; A007947(n-a)*A007947(a)A007947((n-a)*a)); m; }

A147804 Least m coprime to 7 minimizing A007947(m*(7^n-m)).

Original entry on oeis.org

1, 1, 100, 1, 423, 28561, 3072, 124609, 119232
Offset: 1

Views

Author

M. F. Hasler, Nov 13 2008

Keywords

Comments

The minima are given in A147799.
This is related to the abc conjecture: Since m is coprime to 7, it is also coprime to 7^n and thus to 7^n-m. Thus the squarefree kernel A007947(m*(7^n-m)*7^n) = 7*A007947(m(7^n-m)).

Crossrefs

Cf. A007947, A147799 (value of minima), A143700, A147802, A147803 (analog for 2^n, 3^n, 5^n), A147300 (analog for any number).

Programs

  • PARI
    A147804(n,p=7)={my(b, m=3*n=p^n, t); for(a=1, n\2, a%p || next; m>2*(t=A007947(a)) || next; m>(t*=A007947(n-a)) || next; m=t; b=a); b; }

Extensions

Typo in title corrected by M. F. Hasler, Nov 17 2008

A147798 Minimal value of A007947(m*(11^n-m)) with m coprime to 11.

Original entry on oeis.org

6, 30, 30, 390, 3162, 2730, 17706
Offset: 1

Views

Author

M. F. Hasler, Dec 06 2008

Keywords

Comments

The minima are reached for m values given in A147805.

Crossrefs

Cf. A007947, A147298, A147799, A147800, A147801, A147802, A147803, A147804, A147805.

Programs

A147805 Least m coprime to 11 minimizing A007947(m*(11^n-m)).

Original entry on oeis.org

2, 1, 81, 16, 8748, 91, 1489347
Offset: 1

Views

Author

M. F. Hasler, Dec 06 2008

Keywords

Comments

The values of the minima are given in A147798.

Crossrefs

Cf. A007947, A147298, A147798, A147799, A147800, A147801, A147802, A147803, A147804.

Programs

Showing 1-4 of 4 results.

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

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