A087316 a(n) = Sum_{k=1..n} prime(k)^prime(n-k+1).

4, 17, 84, 545, 7824, 281771, 51540600, 3347558057, 1146374959980, 288113965730819, 529172633067826888, 283453407513524913023, 4122282265785671687518812, 1586581830624893452605127040309, 412109111737176949907195758658736

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n=1..50

Example

Examples from Jonathan Vos Post, Jan 06 2006: (Start)
a(1) = 4 because prime(1)^prime(1) = 2^2 = 4.
a(2) = 17 because prime(1)^prime(2) + prime(2)^prime(1) = 2^3 + 3^2 = 17.
a(3) = 84 because 2^5 + 3^3 + 5^2 = 84.
a(4) = 545 = 2^7 + 3^5 + 5^3 + 7^2.
a(5) = 7824 = 2^11 + 3^7 + 5^5 + 7^3 + 11^2.
a(6) = 281771 = 2^13 + 3^11 + 5^7 + 7^5 + 11^3 + 13^2.
a(7) = 51540600 = 2^17 + 3^13 + 5^11 + 7^7 + 11^5 + 13^3 + 17^2.
a(8) = 3347558057 = 2^19 + 3^17 + 5^13 + 7^11 + 11^7 + 13^5 + 17^3 + 19^2.
a(9) = 1146374959980 = 2^23 + 3^19 + 5^17 + 7^13 + 11^11 + 13^7 + 17^5 + 19^3 + 23^2. (End)

Maple

a:=n->sum(ithprime(k)^ithprime(n-k+1), k=1..n): seq(a(n), n=1..16); # Emeric Deutsch, Apr 13 2005

Prog

(PARI) a(n) = sum(k=1, n, prime(k)^prime(n-k+1)); \\ Michel Marcus, Aug 20 2019
(Python)
from sympy import prime
def a(n): return sum(prime(k)**prime(n-k+1) for k in range(1, n+1))
print([a(n) for n in range(1, 16)]) # Michael S. Branicky, Apr 17 2021

Crossrefs

Cf. A000040, A005408, A087315, A113122, A113153, A113154.

Sequence in context: A200716 A093904 A093344 * A104979 A081052 A020074

Adjacent sequences: A087313 A087314 A087315 * A087317 A087318 A087319

Keyword

nonn

Author

Amarnath Murthy, Sep 03 2003

Extensions

More terms from Sam Alexander, Oct 20 2003

Further terms from Emeric Deutsch, Apr 13 2005

Edited by N. J. A. Sloane, Aug 19 2008 at the suggestion of R. J. Mathar

Status

approved