OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..694
EXAMPLE
15 = 5*6/2 = 1111_2.
21 = 6*7/2 = 111_4.
91 = 13*14/2 = 111_9.
171 = 18*19/2 = 333_7.
MAPLE
N:= 10^9: # to get all entries <= N
S:= {}:
for b from 2 to floor(sqrt(N)) do
for k from 3 do
r:= (b^k-1)/(b-1);
if r > N then break fi;
for a from 1 to min(b-1, N/r) do
if issqr(1+8*r*a) then
S:= S union {r*a}
fi
od
od
od:
sort(convert(S, list));
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Robert Israel, Jun 09 2016
STATUS
approved