A245469 - OEIS

%I #8 Aug 08 2014 18:25:32

%S 432,537,3954,4641,5394,7487,7889,12640,20999,23099,25990,35960,38320,

%T 39479,41569,44628,54880,58302,65569,67172,73321,85277,92939,106750,

%U 118240,131652,153912,192632,245019,258852,273819,278389,303769,324269,388494,393269,395454

%N 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.

%e V(3954) = 7249 and sigma(3954) = sigma(7249) = 7920.

%p with(numtheory): V:=proc(t) local j, w, x, y; x:=t; y:=[]; while x>0 do

%p y:=[x mod 10, op(y)]; x:=trunc(x/10); od; x:=(y[nops(y)]+y[1]) mod 10;

%p for j from 1 to nops(y)-1 do x:=x*10+((y[j]+y[j+1]) mod 10); od; x; end:

%p P:=proc(q) local n; for n from 10 to q do if sigma(n)=sigma(V(n))

%p then print(n); fi; od; end: P(10^10);

%Y Cf. A000203, A243993, A245252, A245468.

%K nonn,base

%O 1,1

%A _Paolo P. Lava_, Jul 23 2014