OFFSET
1,2
COMMENTS
The primes fitting exactly in a "Primes-digits square" are given by A158024. Terms computed by Jean-Marc Falcoz.
LINKS
Robert Israel, Table of n, a(n) for n = 1..3000
Eric Angelini, Digit Spiral
E. Angelini, Digit Spiral [Cached copy, with permission]
EXAMPLE
...2...23...2357
.......57...1113
............1719
............2329
The above squares, filled exactly by a subsequence of consecutive primes starting with 2 have sides 1, 2, 4. There is no side-3 square with this property. The next properly filled square will have side 6.
MAPLE
X:= 0: p:= 1:
Res:= NULL: count:= 0:
while count < 100 do
p:= nextprime(p);
X:= X + ilog10(p) + 1;
if issqr(X) then Res:= Res, sqrt(X); count:= count+1: fi
od:
Res; # Robert Israel, Jan 13 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini, Mar 11 2009
STATUS
approved