A245468 Numbers x such that sigma(x)=sigma(T(x)), where sigma(x) is the sum of the divisors of x and T(x) the transform defined in A243993.

204, 395, 506, 583, 612, 627, 718, 795, 975, 2012, 3188, 3690, 7198, 7881, 11472, 21280, 34040, 41310, 49021, 53314, 94363, 107348, 128616, 201804, 203912, 204204, 204435, 207390, 315244, 321010, 345990, 347484, 388297, 395395, 400020, 400352, 402815, 404576

Offset

1,1

Links

Table of n, a(n) for n=1..38.

Example

T(3188) = 4961 and sigma(3188) = sigma(4961) = 5586.

Maple

with(numtheory);
T:=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; w:=(y[nops(y)]+y[1]) mod 10;
x:=0; for j from 1 to nops(y)-1 do x:=x*10+((y[j]+y[j+1]) mod 10); od; x:=x*10+w; end:
P:=proc(q) local n; for n from 10 to q do if sigma(n)=sigma(T(n))
then print(n); fi; od; end: P(10^10);

Crossrefs

Cf. A000203, A243993, A245252, A245469.

Sequence in context: A271643 A108877 A163393 * A154518 A249285 A292346

Adjacent sequences: A245465 A245466 A245467 * A245469 A245470 A245471

Keyword

nonn,base

Author

Paolo P. Lava, Jul 23 2014

Status

approved