A161669 Sum_{j=k(n)..prime(n)} j where k is the n-th nonprime nonnegative integer.

3, 6, 9, 13, 38, 55, 108, 124, 185, 330, 376, 550, 671, 736, 897, 1155, 1470, 1566, 1927, 2178, 2266, 2664, 2958, 3444, 4158, 4521, 4653, 5037, 5215, 5580, 7182, 7656, 8418, 8602, 9999, 10251, 11128, 12040, 12597, 13566, 14570, 14875, 16683, 16951, 17612

Offset

1,1

Links

Table of n, a(n) for n=1..45.

Example

n  k(n)  prime(n)  Sum_{j=k(n)..prime(n)} j
=  ====  ========  ========================
1    0       2               0 + 1 + 2 =  3 = a(1)
2    1       3               1 + 2 + 3 =  6 = a(2)
3    4       5                   4 + 5 =  9 = a(3)
4    6       7                   6 + 7 = 13 = a(4)
5    8      11         8 + 9 + 10 + 11 = 38 = a(5)

Prog

(PARI) k=0; p=2; for(i=1, 1e2, s=p*(p+1)/2-k*(k-1)/2; print1(s", "); p=nextprime(p+1); while(isprime(k++), ))

Crossrefs

Sequence in context: A316531 A242339 A086838 * A128261 A310162 A310163

Adjacent sequences: A161666 A161667 A161668 * A161670 A161671 A161672

Keyword

nonn,base,easy

Author

Juri-Stepan Gerasimov, Jun 16 2009, Jun 27 2009

Extensions

Corrected and extended by Charles R Greathouse IV, Mar 25 2010

Name clarified and Example section edited by Jon E. Schoenfield, Feb 10 2019

Status

approved