login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sides of the successive squares are given by A158025. 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 primes fitting exactly in the SE corner of the above squares are 2, 7, 29. There is no 3X3 square where this is possible.

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

CROSSREFS

Sequence in context: A285790 A083016 A062064 * A166940 A166939 A261182

Adjacent sequences:  A158021 A158022 A158023 * A158025 A158026 A158027

KEYWORD

base,nonn

AUTHOR

Eric Angelini, Mar 11 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 03:54 EDT 2020. Contains 337289 sequences. (Running on oeis4.)