OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..65 (terms < 3*10^9)
EXAMPLE
For n = 232477 we can consider 232477 = 2 U 32477 and sigma(232477) = 265696, sigma(2) = 3, sigma(32477) = 33216 and 265696 - 232477 = 33219 = 3 + 33216.
For n = 251189 we can consider 251189 = 25 U 1189 and sigma(251189) = 252480, sigma(25) = 31, sigma(1189) = 1260 and 252480 - 251189 = 1291 = 31 + 1260.
MAPLE
with(numtheory);
T:=proc(t) local w, x, y; x:=t; y:=0; while x>0 do x:=trunc(x/10); y:=y+1; od; end:
P:=proc(q) local a, b, c, d, i, n; for n from 1 to q do a:=sigma(n); b:=T(n);
for i from 1 to b-1 do c:=trunc(n/10^i); d:=n-c*10^i;
if sigma(c)+sigma(d)=a-n then print(n); break; fi; od; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn,base,hard
AUTHOR
Paolo P. Lava, Mar 21 2014
EXTENSIONS
a(19)-a(32) from Giovanni Resta, Mar 21 2014
STATUS
approved