A072433 Numbers n for which there are exactly nine k such that n = k + reverse(k).

99, 110, 121, 909, 929, 949, 969, 989, 1009, 1010, 1029, 1030, 1049, 1050, 1069, 1070, 1089, 1090, 1110, 1130, 1150, 1170, 1190, 1881, 2101, 3223, 4763, 9009, 10010, 10989, 11990, 16236, 17776, 18081, 18281, 18481, 18681, 18881, 18898

Offset: 1

Author

Klaus Brockhaus, Jun 17 2002

Keywords

• base
• nonn

Comments

Subsequence of A067030. First term is A072041(9).

Contains 9*10^k+9 for k>=1 and 10^k+10 for k>=2. - Robert Israel, Jul 12 2019

Examples

			99 = k + reverse(k) for k = 18, 27, 36, 45, 54, 63, 72, 81, 90.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..422
• Index entries for sequences related to Reverse and Add!

Crossrefs

Cf. A067030, A072041.

Programs

ARIBAS

var n,k,c,i,rev: integer; st,nst: string; end; m := 9; for n := 0 to 19500 do k := n div 2; c := 0; while k <= n and c < m + 1 do st := itoa(k); nst := ""; for i := 0 to length(st) - 1 do nst := concat(st[i],nst); end; rev := atoi(nst); if n = k + rev then inc(c); if k mod 10 <> 0 and k <> rev then inc(c); end; end; inc(k); end; if c = m then write(n,","); end; end;

Maple

N:= 10^5:
revdigs:= proc(n) local L,i;
  L:= convert(n,base,10);
  add(L[-i]*10^(i-1),i=1..nops(L))
end proc:
V:= Vector(N):
for x from 1 to N do
  v:= x + revdigs(x);
  if v <= N then V[v]:= V[v]+1 fi;
od:
select(t -> V[t]=10, [$1..N]); # Robert Israel, Jul 12 2019

Extensions

Offset changed by Robert Israel, Jul 12 2019