login
A069672
Largest n-digit triangular number with minimum digit sum.
0
1, 10, 300, 3003, 20100, 112101, 2001000, 33020001, 200010000, 3200120001, 20000100000, 320001200001, 2000001000000, 32000012000001, 200000010000000, 3200000120000001, 20000000100000000, 320000001200000001, 2000000001000000000, 32000000012000000001, 200000000010000000000, 3200000000120000000001, 20000000000100000000000, 320000000001200000000001, 2000000000001000000000000, 32000000000012000000000001, 200000000000010000000000000, 3200000000000120000000000001, 20000000000000100000000000000, 320000000000001200000000000001
OFFSET
1,2
COMMENTS
Does the obvious pattern continue? - Vladeta Jovovic, Apr 07 2002
MAPLE
F:= proc(d)
local s, P, nP, S, x, bestx;
bestx:= 0;
for s in [1, 3, 6, 9] do
for P in map(op @combinat:-permute, combinat:-partition(s)) do
nP:= nops(P);
for S in map(t -> [d-1, op(t)], combinat:-choose([$0..d-2], nP-1)) do
x:= add(P[i]*10^S[i], i=1..nP);
if x > bestx and issqr(1+8*x) then bestx:= x fi;
od;
od;
if bestx > 0 then return bestx fi;
od;
end proc:
seq(F(d), d=1..30); # Robert Israel, May 25 2016
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Apr 06 2002
EXTENSIONS
More terms from Vladeta Jovovic, Apr 07 2002
a(15)..a(30) from Robert Israel, May 25 2016
STATUS
approved