A343402 Numbers k such that A260815(k) > A260815(k-1)+1.

3, 4, 23, 29, 39, 1559, 1593, 2435519, 2435534, 2485805, 2485806, 2485810, 2485827, 2486989, 5936893149287, 5936893149290, 5936949030071, 5936949030092, 5936949030103, 5936949030105, 5936949030115, 5936949030121, 35246700334321411113125039, 1242329884457453073932774588160466662938743561876559

Offset

1,1

Links

Table of n, a(n) for n=1..24.

Example

a(3) = 23 is in the sequence because A260815(23) - A260815(22) = 575 - 46 > 1.

Maple

G:= proc(nv)
  local n, v, k, np;
  n:= nv[1]; v:= nv[2];
  k:= min(seq((-n-1) mod p, p = numtheory:-factorset(v-n-1)));
  np:= n+k+1;
  [np, v+k+igcd(np, v+k)^2]
end proc:
R:= 3: t:= [3, 12]:
for i from 2 to 24 do
  t:= G(t);
  R:= R, t[1];
od:
R;

Mathematica

2 + Position[Differences @ Nest[Append[#1, #1[[-1]] + GCD[#2, #1[[-1]]]^2] & @@ {#, Length[#] + 2} &, {3}, 10000], _?(# > 1 &)] // Flatten (* Amiram Eldar, Apr 14 2021 after Michael De Vlieger at A260815 *)

Crossrefs

Cf. A260815.

Sequence in context: A042595 A002351 A042035 * A030980 A041861 A042377

Adjacent sequences: A343399 A343400 A343401 * A343403 A343404 A343405

Keyword

nonn

Author

Robert Israel, Apr 13 2021

Status

approved