A239563 Numbers n such that there are a, b with abs(sigma(a) - sigma(b)) = sigma(n) - n and a U b = n, where U is decimal concatenation.

23, 47, 139, 529, 611, 911, 1109, 1445, 1621, 2003, 2521, 2531, 4007, 4361, 4879, 7169, 9011, 9013, 9481, 13009, 18883, 22081, 24257, 25031, 45349, 49901, 56081, 90011, 98941, 99101, 133705, 160031, 169181, 200003, 202289, 210181, 250031, 307289, 336961, 357101

Offset: 1

Author

Paolo P. Lava, Mar 21 2014

Keywords

• nonn
• base

Examples

			For n = 9481 we can consider 9481 = 9 U 481 and sigma(9481) = 10000, sigma(481) = 532, sigma(9) = 13 and 532 - 13 = 519 = 10000 - 9481.
		

Links

• Paolo P. Lava and Giovanni Resta, Table of n, a(n) for n = 1..207(terms < 3*10^9, first 50 terms from Paolo P. Lava)

Crossrefs

Cf. A000203, A239562.

Programs

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 abs(sigma(c)-sigma(d))=a-n then print(n); break; fi;
od; od; end: P(10^9);