login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A076943 Smallest k > 0 such that n*k + 1 is an n-th power. 7
1, 4, 21, 20, 1555, 2604, 299593, 820, 29127, 348678440, 67546215517, 20345052, 61054982558011, 281241170407092, 76861433640456465, 2690420, 128583032925805678351, 211927625868, 275941052631578947368421, 174339220 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Marius A. Burtea, Table of n, a(n) for n = 1..150

FORMULA

a(n) <= ((n+1)^n - 1) / n.

a(p^k) = ((p+1)^(p^k) - 1) / p^k. - Charlie Neder, May 23 2019

a(2*p) = ((2*p-1)^(2*p) - 1) / (2*p). - Charlie Neder, May 23 2019

EXAMPLE

For n = 7, 1 + 7*a(7) = 1 + 7*299593 = 2097152 = 2^21 = 8^7.

For n = 10, 1 + 10*a(10) = 1 + 10*348678440 = 3486784401 = 3^20 = 9^10. - Marius A. Burtea, Jun 01 2019

MATHEMATICA

Do[k = 2; While[ !IntegerQ[(k^n - 1)/n], k++ ]; Print[(k^n - 1)/n], {n, 1, 20}] (* Robert G. Wilson v, Oct 21 2002 *)

PROG

(MAGMA) sol:=[];

for u in [1..20] do

   for k in [2..100] do

      if IsIntegral((k^u-1)/u) then sol[u]:=(k^u-1)/u; break; end if;

   end for;

end for;

sol; // Marius A. Burtea, Jun 01 2019

CROSSREFS

Cf. A076942, A076944, A074792.

Sequence in context: A144292 A338421 A329404 * A138228 A303722 A305225

Adjacent sequences:  A076940 A076941 A076942 * A076944 A076945 A076946

KEYWORD

nice,nonn

AUTHOR

Amarnath Murthy, Oct 19 2002

EXTENSIONS

Edited, corrected and extended by Robert G. Wilson v, Oct 21 2002

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 22 14:30 EDT 2021. Contains 345380 sequences. (Running on oeis4.)