

A034276


Smallest prime that generates a prime pyramid of height n.


3



11, 29, 2, 5, 41, 251, 43, 145577, 51941, 4372877, 26901631, 366636187, 15387286403, 218761753811, 3313980408469
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OFFSET

1,1


COMMENTS

Let p be prime; look for the smallest prime in {1p1, 3p3, 7p7, 9p9}, where '' stands for concatenation; repeat until no such prime can be found; then height(p) = number of rows in pyramid.
a(13) > 10^10.  Donovan Johnson, Aug 13 2010


LINKS

Table of n, a(n) for n=1..15.
H. Heinz, Patterns in Primes, Illustrating Two Prime Pyramids
Chai Wah Wu, On a conjecture regarding primality of numbers constructed from prepending and appending identical digits, arXiv:1503.08883 [math.NT], 2015.


EXAMPLE

Example for p=43: 43 3433 334333 93343339 3933433393 939334333939 39393343339393, stop; height(43)=7.


CROSSREFS

Cf. A047076, A053600, A052205, A256957, A052091, A052092.
Sequence in context: A061086 A201633 A274130 * A245169 A323822 A196357
Adjacent sequences: A034273 A034274 A034275 * A034277 A034278 A034279


KEYWORD

nonn,nice,base,more


AUTHOR

Felice Russo, Jan 25 2000


EXTENSIONS

More terms from Naohiro Nomoto, Jul 14 2001
a(11)a(12) from Donovan Johnson, Aug 13 2010
a(13) from Chai Wah Wu, Apr 10 2015
a(14)a(15) from Giovanni Resta, May 15 2020


STATUS

approved



