A072432 Numbers n for which there are exactly eight k such that n = k + reverse(k).

88, 808, 828, 848, 868, 888, 908, 928, 948, 968, 988, 1131, 1151, 1171, 1191, 1211, 1231, 1251, 1271, 1291, 1771, 2211, 2332, 3652, 4114, 5874, 8008, 9988, 12991, 15125, 16885, 17071, 17271, 17347, 17471, 17671, 17871, 18071, 18271, 18471

Offset

1,1

Comments

Subsequence of A067030. First term is A072041(8).

Contains 8*10^k+8 for all k>=1. - Robert Israel, Jul 12 2019

Links

Robert Israel, Table of n, a(n) for n = 1..673

Index entries for sequences related to Reverse and Add!

Example

88 = k + reverse(k) for k = 17, 26, 35, 44, 53, 62, 71, 80.

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]=8, [$1..N]); # Robert Israel, Jul 12 2019

Mathematica

krk8Q[n_]:=Count[Range[n-1], _?(#+FromDigits[Reverse[ IntegerDigits[#]]] ==n&)]==8; Select[Range[20000], krk8Q]  (* Harvey P. Dale, Apr 02 2011 *)

Prog

(ARIBAS) var n, k, c, i, rev: integer; st, nst: string; end; m := 8; for n := 0 to 18800 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;

Crossrefs

Cf. A067030, A072041.

Sequence in context: A297228 A137124 A194651 * A136951 A136933 A136958

Adjacent sequences: A072429 A072430 A072431 * A072433 A072434 A072435

Keyword

base,nonn

Author

Klaus Brockhaus, Jun 17 2002

Extensions

Offset changed by Robert Israel, Jul 12 2019

Status

approved