This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
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
n a(n) digit sum #dgts mean digit value -- -------------------- --------- ----- ---------------- 1 0 0 1 0 2 1 1 1 1 3 3 3 1 3 4 6 6 1 6 5 78 15 2 7.5 6 686999778 69 9 7.66666666666... 7 9876799878 78 10 7.8 8 89996788896 87 11 7.90909090909... 9 77779987999896 111 14 7.92857142857... 10 589598998999878 120 15 8 11 999699998689998991 145 18 8.05555555555... 12 9988894989978899995 154 19 8.10526315789... 13 95898999989999989765 163 20 8.15
seq = {}; max = -1; Do[If[(m = Mean @ IntegerDigits[(t = n*(n + 1)/2)]) > max, max = m; AppendTo[seq, t]], {n, 0, 10^6}]; seq (* Amiram Eldar, Dec 03 2021 *)
def meandigval(n): s = str(n); return sum(map(int, s))/len(s)
def afind(limit):
alst, k, t, record = [], 0, 0, -1
while t <= limit:
mdv = meandigval(t)
if mdv > record:
print(t, end=", ")
record = mdv
k += 1
t += k
afind(10**14) # Michael S. Branicky, Dec 03 2021
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