The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A068147 Primes in right concatenation of triangular numbers. 1
 31, 631, 10631, 55453628211510631, 786655453628211510631, 10591786655453628211510631 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS No further terms up to 1,000 triangular numbers.  From Harvey P. Dale, Jul 23 2012 REFERENCES Shyam Sunder Gupta, Smarandache Sequence of Triangular Numbers, Smarandache Notions Journal, (to appear in Vol. 14, 2003). LINKS EXAMPLE a(2)=631 because in A078891 631 is the second prime. 10631 is a prime and the concatenation of 10, 6, 3, 1. MATHEMATICA a = 1; Do[ a = ToExpression[ StringJoin[ ToString[n(n + 1)/2], ToString[a]]]; If[ PrimeQ[a], Print[a]], {n, 2, 250} ] nn=50; With[{c=Accumulate[Range[nn]]}, Select[Table[FromDigits[ Flatten[ IntegerDigits/@ Reverse[Take[c, n]]]], {n, nn}], PrimeQ]] (* Harvey P. Dale, Jul 23 2012 *) CROSSREFS Primes in A078891. Sequence in context: A089758 A078891 A078914 * A025009 A028004 A025007 Adjacent sequences:  A068144 A068145 A068146 * A068148 A068149 A068150 KEYWORD base,hard,more,nonn,less AUTHOR Amarnath Murthy, Feb 23 2002 EXTENSIONS Edited by Robert G. Wilson v, Mar 01 2002 Entry revised Feb 15 2004 STATUS approved

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

Last modified June 24 21:51 EDT 2022. Contains 354830 sequences. (Running on oeis4.)