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A072430
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Numbers n for which there are exactly six k such that n = k + reverse(k).
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1
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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
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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66 = k + reverse(k) for k = 15, 24, 33, 42, 51, 60; 626 = k + reverse(k) for k = 115, 214, 313, 412, 511, 610.
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MAPLE
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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
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PROG
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(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;
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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