A138418 a(n) = ((n-th prime)^4-(n-th prime)^2)/2.

6, 36, 300, 1176, 7260, 14196, 41616, 64980, 139656, 353220, 461280, 936396, 1412040, 1708476, 2438736, 3943836, 6056940, 6921060, 10073316, 12703320, 14196456, 19471920, 23725716, 31367160, 44259936, 52025100, 56270136

Offset: 1

Author

Artur Jasinski, Mar 19 2008

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..200

Programs

Magma

[(NthPrime((n))^4 - NthPrime((n))^2)/2: n in [1..30] ]; // Vincenzo Librandi, Jun 17 2011

Mathematica

a = {}; Do[p = Prime[n]; AppendTo[a, (p^4 - p^2)/2], {n, 1, 50}]; a

PARI

forprime(p=2,1e3,print1((p^4-p^2)/2", ")) \\ Charles R Greathouse IV, Jul 15 2011

Formula

a(n) = A138402(n)/2. - R. J. Mathar, Oct 15 2017

a(n) = binomial(prime(n)^2, 2) = A000217(A001248(n)). - Jon Maiga, Nov 14 2018