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A239566 (Round(c^prime(n)) - 1)/prime(n), where c is the heptanacci constant (A118428). 2
7200, 25562, 332466, 16472758, 61145666, 3200477798, 45473543628, 172043098818, 2478186385762, 137291966046470, 7704742900338106, 29569459376703894, 1681851263230158754, 24987922624169214866, 96433670513455876108, 5566902760779797458210 (list; graph; refs; listen; history; text; internal format)



For n>=7, round(c^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.


Table of n, a(n) for n=7..22.

S. Litsyn and V. Shevelev, Irrational Factors Satisfying the Little Fermat Theorem, International Journal of Number Theory, vol.1, no.4 (2005), 499-512.

V. Shevelev, A property of n-bonacci constant, Seqfan (Mar 23 2014)

Eric Weisstein's World of Mathematics, Heptanacci Constant


All roots of the equation x^7-x^6-x^5-x^4-x^3-x^2-x-1 = 0

are the following: c=1.9919641966050350211,

-0.78418701799584451319 +/- 0.36004972226381653409*i,

-0.24065633852269642508 + /- 0.84919699909267892575*i,

  0.52886125821602342773 +/-  0.76534196109589443115*i.

Absolute values of all roots, except for septanacci constant c, are less than 1.

Conjecture. Absolute values of all roots of the equation x^n - x^(n-1) - ... -x - 1 = 0, except for n-bonacci constant c_n, are less than 1. If the conjecture is valid, then for sufficiently large k=k(n), for all m>=k, we have round(c_n^prime(m)) == 1 (mod 2*prime(m)) (cf. Shevelev link).


Cf. A007619, A007663, A238693, A238697, A238698, A238700, A239502, A239544, A239564, A239565.

Sequence in context: A064979 A204480 A190114 * A236993 A035906 A218513

Adjacent sequences:  A239563 A239564 A239565 * A239567 A239568 A239569




Peter J. C. Moses and Vladimir Shevelev, Mar 21 2014



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Last modified December 8 18:37 EST 2019. Contains 329865 sequences. (Running on oeis4.)