A068147 Primes in right concatenation of triangular numbers.

31, 631, 10631, 55453628211510631, 786655453628211510631, 10591786655453628211510631

Offset

1,1

Comments

No further terms up to 1000 triangular numbers. - Harvey P. Dale, Jul 23 2012

A078891(1201), with 6560 digits, is the next term. - Michael S. Branicky, Jul 01 2023

References

Shyam Sunder Gupta, Smarandache Sequence of Triangular Numbers, Smarandache Notions Journal, (to appear in Vol. 14, 2003).

Links

Table of n, a(n) for n=1..6.

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,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