A332475 - OEIS

%I #9 Feb 14 2020 03:21:52

%S 5,11,37,1738,2772,6600,42251,49913,57816,104754,220324,288350,364452,

%T 792156,1711932,1971475,2607049,2793473,3211933,3521148,3526312,

%U 4012736,5805149,5918276,6522320,6542147,6635436,7612267,12604600,14844791,17078848,19024332,21177516

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

%H Amiram Eldar, <a href="/A332475/b332475.txt">Table of n, a(n) for n = 1..100</a>

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

%t 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

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

%K nonn

%O 1,1

%A _Amiram Eldar_, Feb 13 2020