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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A125130 Successive sums of consecutive primes that form a triangular grid. 0
2, 10, 41, 129, 328, 712, 1371, 2427, 4028, 6338, 9523, 13887, 19580, 26940, 36227, 47721, 61910, 79168, 99685, 124211, 153178, 186914, 225831, 271061, 322858, 382038, 448869, 524451, 608914, 704204, 810459, 927883, 1057828, 1201162 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These sums, for a given n, can be estimated by the following formula. sum est = x^2/(2*log(x)-1) Where x = prime(n*(n-1)/2+n) For example, n = 10000 x = 982555543 sum est = 23889718028585418 sum act = 23904330028803899 Relative Error = 0.00061127001680771897

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

The consecutive primes 2,3,5,7,11,13 form the triangular grid,

....... 2

..... 3 5

... 7 11 13

These consecutive primes add up to 41, the third entry in the table.

PROG

(PARI) g2(n) = for(j=1, n, y=g(j*(j+1)/2); print1(y", ")) g(n) = local(s=0, x); for(x=1, n, s+=prime(x)); s

CROSSREFS

Cf. A078721.

Sequence in context: A127113 A051540 A272135 * A110684 A197175 A297047

Adjacent sequences:  A125127 A125128 A125129 * A125131 A125132 A125133

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Jan 10 2007

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 13:32 EDT 2019. Contains 328093 sequences. (Running on oeis4.)