This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A186506 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. 1
 1, 13, 139, 12739, 1281739, 1281739243, 1281737299243, 12817372218799243, 128173765612218799243, 12196838173765612218799243, 1219683817376590495612218799243, 1219683817714717376590495612218799243, 1219683853144117714717376590495612218799243, 12196838531441159432317714717376590495612218799243, 121968385314411594323177147478296917376590495612218799243 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This is not really well-defined, but it is a published sequence of some recreational interest. REFERENCES C. K. Caldwell and A. Rupinski, Pyramids of 3-powerful primes, Mathematical Spectrum, 43 (No. 2, 2010/2011), 65-69. LINKS C. K. Caldwell and A. Rupinski, Pyramids of 3-powerful primes (abstract), Mathematical Spectrum, 43 (No. 2, 2010/2011), 65-69. EXAMPLE (1) 13 139 12739 1281739 1281739243 1281737299243 12817372218799243 128173765612218799243 12196838173765612218799243 1219683817376590495612218799243 1219683817714717376590495612218799243 1219683853144117714717376590495612218799243 12196838531441159432317714717376590495612218799243 121968385314411594323177147478296917376590495612218799243 CROSSREFS Cf. A186507. Sequence in context: A195464 A064103 A266630 * A051639 A138931 A157160 Adjacent sequences:  A186503 A186504 A186505 * A186507 A186508 A186509 KEYWORD base,nonn,fini,full AUTHOR N. J. A. Sloane, Feb 22 2011 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.

Last modified September 17 10:52 EDT 2019. Contains 327129 sequences. (Running on oeis4.)