OFFSET
1,3
COMMENTS
a(n) is also the area under the curve of the function pi(x) from 0 to prime(n). - Omar E. Pol, Nov 13 2013
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
Christian Axler, On a sequence involving the prime numbers, arXiv:1504.04467 [math.NT], 2015 and J. Int. Seq. 18 (2015) # 15.7.6.
Christian Axler, Improving the Estimates for a Sequence Involving Prime Numbers, arXiv:1706.04049 [math.NT], 2017.
FORMULA
a(n) = Sum_{k=1..n-1} k*A001223(k). - François Huppé, Mar 16 2022
EXAMPLE
From Omar E. Pol, Apr 27 2015: (Start)
For n = 5 the 5th prime is 11 and the sum of first five primes is 2 + 3 + 5 + 7 + 11 = 28, so a(5) = 5*11 - 28 = 27.
Illustration of a(5) = 27:
Consider a diagram in the first quadrant of the square grid in which the number of cells in the n-th horizontal bar is equal to the n-th prime, as shown below:
. _ _ _ _ _ _ _ _ _ _ _
. 11 |_ _ _ _ _ _ _ _ _ _ _|
. 7 |_ _ _ _ _ _ _|* * * *
. 5 |_ _ _ _ _|* * * * * *
. 3 |_ _ _|* * * * * * * *
. 2 |_ _|* * * * * * * * *
.
a(5) is also the area (or the number of cells, or the number of *'s) under the bar's structure of prime numbers: a(5) = 1 + 4 + 6 + 16 = 27.
(End)
MATHEMATICA
nn = 100; p = Prime[Range[nn]]; Range[nn] p - Accumulate[p] (* T. D. Noe, May 02 2011 *)
PROG
(Sage) [n*nth_prime(n) - sum(nth_prime(j) for j in range(1, n+1)) for n in range(1, 45)] # Danny Rorabaugh, Apr 18 2015
(PARI) vector(80, n, n*prime(n) - sum(k=1, n, prime(k))) \\ Michel Marcus, Apr 20 2015
(Python)
from sympy import prime, primerange
def A152535(n): return (n-1)*(p:=prime(n))-sum(primerange(p)) # Chai Wah Wu, Jan 01 2024
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Dec 06 2008
STATUS
approved