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A245469
Numbers x such that sigma(x)=sigma(V(x)), where sigma(x) is the sum of the divisors of x and V(x) the transform defined in A245252.
1
432, 537, 3954, 4641, 5394, 7487, 7889, 12640, 20999, 23099, 25990, 35960, 38320, 39479, 41569, 44628, 54880, 58302, 65569, 67172, 73321, 85277, 92939, 106750, 118240, 131652, 153912, 192632, 245019, 258852, 273819, 278389, 303769, 324269, 388494, 393269, 395454
OFFSET
1,1
EXAMPLE
V(3954) = 7249 and sigma(3954) = sigma(7249) = 7920.
MAPLE
with(numtheory): V:=proc(t) local j, w, x, y; x:=t; y:=[]; while x>0 do
y:=[x mod 10, op(y)]; x:=trunc(x/10); od; x:=(y[nops(y)]+y[1]) mod 10;
for j from 1 to nops(y)-1 do x:=x*10+((y[j]+y[j+1]) mod 10); od; x; end:
P:=proc(q) local n; for n from 10 to q do if sigma(n)=sigma(V(n))
then print(n); fi; od; end: P(10^10);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava, Jul 23 2014
STATUS
approved