proposed

approved

editing

proposed

a(1) = 17 = 16 *( 1^3) *( 1!) + 1 is prime.

a(2) = 257 = 16 *( 2^3) *( 2!) + 1 is prime.

a(3) = 2591 = 16 *( 3^3) *( 3!) - 1 is prime.

a(4) = 2593 = 16 *( 3^3) *( 3!) + 1 is prime.

a(5) = 239999 = 16 *( 5^3) *( 5!) - 1 is prime.

a(6) = 2488319 = 16 *( 6^3) *( 6!) - 1 is prime.

a(7) = 27659519 = 16 *( 7^3) *( 7!) - 1 is prime.

a(8) = 27659521 = 16 *( 7^3) *( 7!) + 1 is prime.

a(9) = 330301441 = 16 *( 8^3) *( 8!) + 1 is prime.

a(10) = 4232632319 = 16 *( 9^3) *( 9!) - 1 is prime.

a(11) = 58060799999 = 16 *( 10^3) *( 10!) - 1 is prime.

a(12) = 13243436236801 = 16 *( 12^3) *( 12!) + 1 is prime.

a(13) = 70614415872000001 = 16 *( 15^3) *( 15!) + 1 is prime.

proposed

editing

editing

proposed

A174335 := proc(n) 16*n^3*n! ; end proc: for i from 1 to 60 do a := A174335(i) ; if isprime(a-1) then printf("%d, ", a-1) ; end if; if isprime(a+1) then printf("%d, ", a+1) ; end if; end do: [From _# _R. J. Mathar_, Apr 15 2010]

approved

editing

_Jonathan Vos Post (jvospost3(AT)gmail.com), _, Mar 19 2010

A174335 := proc(n) 16*n^3*n! ; end proc: for i from 1 to 60 do a := A174335(i) ; if isprime(a-1) then printf("%d, ", a-1) ; end if; if isprime(a+1) then printf("%d, ", a+1) ; end if; end do: [From _R. J. Mathar (mathar(AT)strw.leidenuniv.nl), _, Apr 15 2010]

One more term from _R. J. Mathar (mathar(AT)strw.leidenuniv.nl), _, Apr 15 2010

proposed

approved

17, 257, 2591, 2593, 239999, 2488319, 27659519, 27659521, 330301441, 4232632319, 58060799999, 13243436236801, 70614415872000001, 3429209878281350809286344704000001, 1665505492033205854772229590583093971095149084672000000001

easy,more,nonn

approved

proposed

Primes of the form A174335(i)-1 or A174335(i)+1.

17, 257, 2591, 2593, 239999, 2488319, 27659519, 27659521, 330301441, 4232632319, 58060799999, 13243436236801, 70614415872000001, 3429209878281350809286344704000001

1,1

a(n) = {A000040(i)} INTERSECTION ({16*(j^3)*(j!) - 1} UNION {16*(k^3)*(k!) - 1}).

a(1) = 17 = 16*(1^3)*(1!) + 1 is prime.

a(2) = 257 = 16*(2^3)*(2!) + 1 is prime.

a(3) = 2591 = 16*(3^3)*(3!) - 1 is prime.

a(4) = 2593 = 16*(3^3)*(3!) + 1 is prime.

a(5) = 239999 = 16*(5^3)*(5!) - 1 is prime.

a(6) = 2488319 = 16*(6^3)*(6!) - 1 is prime.

a(7) = 27659519 = 16*(7^3)*(7!) - 1 is prime.

a(8) = 27659521 = 16*(7^3)*(7!) + 1 is prime.

a(9) = 330301441 = 16*(8^3)*(8!) + 1 is prime.

a(10) = 4232632319 = 16*(9^3)*(9!) - 1 is prime.

a(11) = 58060799999 = 16*(10^3)*(10!) - 1 is prime.

a(12) = 13243436236801 = 16*(12^3)*(12!) + 1 is prime.

a(13) = 70614415872000001 = 16*(15^3)*(15!) + 1 is prime.

A174335 := proc(n) 16*n^3*n! ; end proc: for i from 1 to 60 do a := A174335(i) ; if isprime(a-1) then printf("%d, ", a-1) ; end if; if isprime(a+1) then printf("%d, ", a+1) ; end if; end do: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010]

Cf. A000040, A000142, A000578, A174335.

easy,more,nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 19 2010

One more term from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010

approved