login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A117112 Primes expressible as the sum of two triangular numbers (including zero). 6
2, 3, 7, 11, 13, 29, 31, 37, 43, 61, 67, 73, 79, 83, 97, 101, 127, 137, 139, 151, 157, 163, 181, 191, 193, 199, 211, 227, 241, 263, 277, 281, 307, 331, 353, 367, 373, 379, 389, 409, 421, 433, 443, 461, 463, 487, 499, 541, 571, 577, 587, 601, 619, 631, 659, 661 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A117048 for the primes that are the sum of two positive triangular numbers. The only difference is that the prime 3 occurs here.

LINKS

Table of n, a(n) for n=1..56.

FORMULA

A000040 intersect A020756. - Jonathan Vos Post, Apr 17 2006

EXAMPLE

2 = 1 + 1

3 = 0 + 3

7 = 1 + 6

and so on.

MATHEMATICA

tri = Table[n (n + 1)/2, {n, 0, 40}]; Select[Union[Flatten[Outer[Plus, tri, tri]]], # <= tri[[-1]]+1 && PrimeQ[#] &] (* T. D. Noe, Apr 07 2011 *)

CROSSREFS

Cf. A000217, A117048.

Sequence in context: A091206 A038963 A167609 * A145032 A233414 A233863

Adjacent sequences:  A117109 A117110 A117111 * A117113 A117114 A117115

KEYWORD

easy,nonn

AUTHOR

Greg Huber, Apr 18 2006

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified November 24 09:00 EST 2014. Contains 249873 sequences.