A072430 Numbers n for which there are exactly six k such that n = k + reverse(k).

66, 143, 606, 626, 646, 666, 686, 706, 726, 746, 766, 786, 1313, 1333, 1353, 1373, 1393, 1413, 1433, 1453, 1473, 1493, 1551, 2222, 2431, 3113, 3762, 4873, 6006, 7986, 13013, 14993, 15051, 15251, 15451, 15651, 15851, 16051, 16126, 16251, 16451

Offset: 1

Author

Klaus Brockhaus, Jun 17 2002

Keywords

• base
• nonn

Comments

Subsequence of A067030. First term is A072041(6).

Includes 6*(10^k+1) for k >= 1. - Robert Israel, Jul 12 2019

Examples

			66 = k + reverse(k) for k = 15, 24, 33, 42, 51, 60; 626 = k + reverse(k) for k = 115, 214, 313, 412, 511, 610.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..628
• 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 := 6; for n := 0 to 17500 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]=6, [$1..N]); # Robert Israel, Jul 12 2019

Extensions

Offset changed to 1 by Robert Israel, Jul 12 2019