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A080454
Smallest multiple of n beginning with the backward concatenation of numbers from (n-1) to 1.
1
0, 10, 21, 3212, 43210, 543210, 6543215, 76543216, 87654321, 9876543210, 109876543216, 11109876543216, 1211109876543216, 131211109876543214, 14131211109876543210, 1514131211109876543216, 1615141312111098765432108
OFFSET
1,2
LINKS
MAPLE
bcat:= proc(n) option remember;
local r;
r:= procname(n-1);
n*10^(1+ilog10(r))+r
end proc:
bcat(1):= 1: bcat(0):= 0:
f:= proc(n) local r, rm, d, w;
r:= bcat(n-1);
rm:= r mod n;
if rm = 0 then return r fi;
for d from 1 do
w:= -10^d*rm mod n;
if w < 10^d then return 10^d*r + w fi
od;
end proc:
map(f, [$1..20]); # Robert Israel, Jul 30 2026
CROSSREFS
Sequence in context: A039821 A109326 A369120 * A226789 A110367 A104865
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Feb 23 2003
EXTENSIONS
Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Jul 04 2003
STATUS
approved