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

Author

Amiram Eldar, Feb 09 2020

Keywords

• nonn
• more

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.

Examples

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

Crossrefs

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

Programs

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