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%I #13 May 18 2013 08:57:20
%S 1,13,139,12739,1281739,1281739243,1281737299243,12817372218799243,
%T 128173765612218799243,12196838173765612218799243,
%U 1219683817376590495612218799243,1219683817714717376590495612218799243,1219683853144117714717376590495612218799243,12196838531441159432317714717376590495612218799243,121968385314411594323177147478296917376590495612218799243
%N An example of a pyramid of numbers that starts with 1 and successive terms are primes formed by inserting the next power of 3 somewhere in the previous term.
%C This is not really well-defined, but it is a published sequence of some recreational interest.
%D C. K. Caldwell and A. Rupinski, Pyramids of 3-powerful primes, Mathematical Spectrum, 43 (No. 2, 2010/2011), 65-69.
%H C. K. Caldwell and A. Rupinski, <a href="http://ms.appliedprobability.org/data/files/Abstracts%2043/43-2-5.pdf">Pyramids of 3-powerful primes (abstract)</a>, Mathematical Spectrum, 43 (No. 2, 2010/2011), 65-69.
%e (1)
%e 13
%e 139
%e 12739
%e 1281739
%e 1281739243
%e 1281737299243
%e 12817372218799243
%e 128173765612218799243
%e 12196838173765612218799243
%e 1219683817376590495612218799243
%e 1219683817714717376590495612218799243
%e 1219683853144117714717376590495612218799243
%e 12196838531441159432317714717376590495612218799243
%e 121968385314411594323177147478296917376590495612218799243
%Y Cf. A186507.
%K base,nonn,fini,full
%O 0,2
%A _N. J. A. Sloane_, Feb 22 2011
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