A260093 Numbers n for which A259124(n) = A259124(n-1) + 1.
20, 49, 2096, 5684, 14847, 440876, 18770091, 40882585915, 5598199195808, 35959924244180
Offset: 1
Programs
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PARI
a259124(n)=sum(y=2, sqrtint(n+1)-1, my(x=(n-y)/(y+1)); if(denominator(x)==1, x+y)); isok(n)= a259124(n) == a259124(n-1) + 1; \\ Michel Marcus, Aug 05 2015
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Python
TOP = 5000*5000 a = [0]*TOP for y in range(2, 5000): z = TOP//y + 1 for x in range(y, z): n = x*y + x + y if n>=TOP: break a[n] += x+y for n in range(1,TOP): if a[n]==a[n-1]+1 and a[n]>0: print(n, end=', ')
Extensions
a(8)-a(9) from Hiroaki Yamanouchi, Aug 24 2015
a(10) from Hiroaki Yamanouchi, Aug 25 2015
Comments