A076286 Numbers of the form (7^{mr}-1)/(7^r-1) for positive integers m, r.

1, 8, 50, 57, 344, 400, 2402, 2451, 2801, 16808, 19608, 117650, 117993, 120100, 137257, 823544, 960800, 5764802, 5767203, 5884901, 6725601, 40353608, 40471600, 47079208, 282475250, 282492057, 288360150, 329554457, 1977326744, 2306881200, 13841287202

Offset: 1

Author

N. J. A. Sloane, Nov 06 2002

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..8539
• T. Chinburg and M. Henriksen, Sums of k-th powers in the ring of polynomials with integer coefficients, Acta Arithmetica, 29 (1976), 227-250.

Crossrefs

Cf. A064896 (k=2), A076270 (k=3), A076275 (k=4), A076284 (k=5), A076285 (k=6), A076287 (k=8), A076288 (k=9), A076289 (k=10).

Programs

Maple

[1,seq(seq((7^(d+r)-1)/(7^r-1),r = sort(convert(numtheory:-divisors(d),list),`>`)),d=1..20)]; # Robert Israel, Aug 27 2018