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A263170
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a(n) = (Sum_{k=1..n} prime(k))^3 - (Sum_{k=1..n} prime(k)^3).
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1
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0, 90, 840, 4410, 20118, 64890, 186168, 440730, 972030, 2094330, 4013850, 7512570, 13279548, 21906810, 34902498, 54772410, 84444690, 124785210, 181983378, 259292154, 358930146, 492406650, 664548816, 889272570, 1186319550, 1559209530, 2012668266, 2568943290, 3232452450, 4031692410
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OFFSET
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1,2
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COMMENTS
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Obviously, a(n) is always an even number.
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LINKS
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FORMULA
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a(n) mod 2 = 0.
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EXAMPLE
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For n = 2, a(2) = (2 + 3)^3 - (2^3 + 3^3) = 90.
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MAPLE
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su := add(ithprime(i), i=1..n) ;
su3 := add(ithprime(i)^3, i=1..n) ;
su^3-su3 ;
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MATHEMATICA
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Table[Sum[Prime@ k, {k, n}]^3 - Sum[Prime[k]^3, {k, n}], {n, 30}] (* Michael De Vlieger, Oct 19 2015 *)
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PROG
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(PARI) a(n) = sum(k=1, n, prime(k))^3 - sum(k=1, n, prime(k)^3);
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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