A332315 Numbers k such that k and k + 1 have the same norm of the sum of divisors in Gaussian integers.

30514, 36777, 43978, 3474262, 5745125, 10628554, 16567494, 40831527, 58008301, 111798477, 142981839, 288834504, 392413941, 580867202, 650141557, 944224497, 967593411, 1874210882, 6306287377, 6442064745, 7377567197, 8121464245

Offset

1,1

Comments

The first term, 30514, is also a number k such that k and k + 1 have the sum divisors in Gaussian integers: -54720 + 48960*i (where i is the imaginary unit). What is the next term with this property?

No more terms below 1.5*10^10.

Links

Table of n, a(n) for n=1..22.

Example

30514 is a term since A103230(30514) = A103230(30515) = 5391360000.

Mathematica

csigma[n_] :=(Abs @ DivisorSigma[1, n, GaussianIntegers -> True])^2; seq = {}; n1 = csigma[1]; Do[n2 = csigma[n]; If[n1 == n2, AppendTo[seq, n - 1]]; n1 = n2, {n, 2, 5*10^5}]; seq

Crossrefs

Cf. A002961, A064125, A103228, A103229, A103230, A293183, A306985.

Sequence in context: A251527 A226528 A278271 * A254976 A234791 A134118

Adjacent sequences: A332312 A332313 A332314 * A332316 A332317 A332318

Keyword

nonn,more

Author

Amiram Eldar, Feb 09 2020

Status

approved