A332475 Numbers k such that k and k + 1 have the same norm of the sum of unitary divisors in Gaussian integers (A332474).

5, 11, 37, 1738, 2772, 6600, 42251, 49913, 57816, 104754, 220324, 288350, 364452, 792156, 1711932, 1971475, 2607049, 2793473, 3211933, 3521148, 3526312, 4012736, 5805149, 5918276, 6522320, 6542147, 6635436, 7612267, 12604600, 14844791, 17078848, 19024332, 21177516

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..100

Example

5 is a term since A332474(5) = A332474(6) = 80.

Mathematica

f[p_, e_] := If[Abs[p] == 1, 1, (p^e + 1)]; normUsigma[n_] := Abs[Times @@ f @@@ FactorInteger[n, GaussianIntegers -> True]]^2; seq = {}; u1 = normUsigma[1]; Do[u2 = normUsigma[n]; If[u1 == u2, AppendTo[seq, n - 1]]; u1 = u2, {n, 2, 10^6}]; seq

Crossrefs

Cf. A002961, A064125, A293183, A306985, A332315, A332472, A332473, A332474.

Sequence in context: A074626 A090186 A205719 * A139515 A038708 A042719

Adjacent sequences: A332472 A332473 A332474 * A332476 A332477 A332478

Keyword

nonn

Author

Amiram Eldar, Feb 13 2020

Status

approved