OFFSET
1,1
EXAMPLE
226 = concat(22,6); 22*23/2 - sigma(22) = 253 - 36 = 217; 6*7/2 - sigma(6) = 21 - 12 = 9. Finally 217 + 9 = 226.
MAPLE
with(numtheory): P:=proc(q) local s, t, k; global n; for n from 1 to q do for k from 1 to ilog10(n) do s:=n mod 10^k; t:=trunc(n/10^k); if s>0 then if s*(s+1)/2-sigma(s)+t*(t+1)/2-sigma(t)=n
then print(n); break; fi; fi; od; od; end: P(10^7);
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Paolo P. Lava, Feb 02 2015
EXTENSIONS
Incorrect term 240 removed by and a(6)-a(7) from Jinyuan Wang, Feb 16 2021
STATUS
approved