A283418 Numbers n such that n and n+1 are primitive abundant.

82004, 158235, 326864, 442035, 516704, 1102724, 1606275, 2151435, 2697435, 2912084, 2921535, 2979675, 3002804, 3241755, 3647475, 4322835, 5801984, 5905844, 6069195, 7251075, 7387604, 7553924, 8272124, 8788724, 9292724, 9909584

Offset

1,1

Comments

Intersection of A091191 and -1 + A091191.

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

82004 is in the sequence because it is abundant (sum divisors = 164640, > 2*82004) and 82005 is also abundant (sum divisors = 165888, > 2*82005).

Mathematica

fQ[m_] := DivisorSigma[1, m] > 2 m;
gQ[m_] := fQ[m] && Union[fQ /@ Rest[Most[Divisors[m]]]] == {False};
V = Select[Range[10^7], gQ]; Intersection[V, V - 1]

Crossrefs

Cf. A091191, A005105, A096399.

Sequence in context: A098187 A146025 A361934 * A330872 A253957 A253964

Adjacent sequences: A283415 A283416 A283417 * A283419 A283420 A283421

Keyword

nonn

Author

Emmanuel Vantieghem, May 02 2017

Status

approved