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A087316
a(n) = Sum_{k=1..n} prime(k)^prime(n-k+1).
10
4, 17, 84, 545, 7824, 281771, 51540600, 3347558057, 1146374959980, 288113965730819, 529172633067826888, 283453407513524913023, 4122282265785671687518812, 1586581830624893452605127040309, 412109111737176949907195758658736
OFFSET
1,1
LINKS
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
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