A158024 Primes p such that all the digits needed to write the consecutive Primes from 2 to p fill exactly a square (no holes, no overlaps).
2, 7, 29, 71, 101, 127, 191, 229, 317, 379, 499, 577, 733, 823, 10867, 11159, 12301, 12577, 13781, 14107, 15391, 15733, 17183, 17509, 19079, 19457, 21023, 21467, 23059, 23549, 25339, 25793, 27733, 28151, 30161, 30697, 32719, 33247, 35401
Offset: 1
Examples
...2...23...2357 .......57...1113 ............1719 ............2329 The primes fitting exactly in the SE corner of the above squares are 2, 7, 29. There is no 3X3 square where this is possible.
Links
- Robert Israel, Table of n, a(n) for n = 1..3000
- Eric Angelini, Digit Spiral
- E. Angelini, Digit Spiral [Cached copy, with permission]
Programs
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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,p; count:= count+1 fi od: Res; # Robert Israel, Jan 13 2020
Comments