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A260093 Numbers n for which A259124(n) = A259124(n-1) + 1.

%I A260093 #23 Nov 13 2024 16:40:53
%S A260093 20,49,2096,5684,14847,440876,18770091,40882585915,5598199195808,
%T A260093 35959924244180
%N A260093 Numbers n for which A259124(n) = A259124(n-1) + 1.
%C A260093 Is the sequence infinite?
%C A260093 a(11) > 5 * 10^13. - _Hiroaki Yamanouchi_, Aug 24 2015
%o A260093 (Python)
%o A260093 TOP = 5000*5000
%o A260093 a = [0]*TOP
%o A260093 for y in range(2, 5000):
%o A260093   z = TOP//y + 1
%o A260093   for x in range(y, z):
%o A260093     n = x*y + x + y
%o A260093     if n>=TOP: break
%o A260093     a[n] += x+y
%o A260093 for n in range(1,TOP):
%o A260093     if a[n]==a[n-1]+1 and a[n]>0: print(n, end=', ')
%o A260093 (PARI) a259124(n)=sum(y=2, sqrtint(n+1)-1, my(x=(n-y)/(y+1)); if(denominator(x)==1, x+y));
%o A260093 isok(n)= a259124(n) == a259124(n-1) + 1; \\ _Michel Marcus_, Aug 05 2015
%Y A260093 Cf. A259124, A259432.
%K A260093 nonn,more
%O A260093 1,1
%A A260093 _Alex Ratushnyak_, Jul 15 2015
%E A260093 a(8)-a(9) from _Hiroaki Yamanouchi_, Aug 24 2015
%E A260093 a(10) from _Hiroaki Yamanouchi_, Aug 25 2015