The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A332315 Numbers k such that k and k + 1 have the same norm of the sum of divisors in Gaussian integers. 1
 30514, 36777, 43978, 3474262, 5745125, 10628554, 16567494, 40831527, 58008301, 111798477, 142981839, 288834504, 392413941, 580867202, 650141557, 944224497, 967593411, 1874210882, 6306287377, 6442064745, 7377567197, 8121464245 (list; graph; refs; listen; history; text; internal format)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 8 15:21 EDT 2021. Contains 343666 sequences. (Running on oeis4.)