A189892 a(n) = n*prime(n) - sum_{i=1..n-1} prime(i).

2, 4, 10, 18, 38, 50, 78, 94, 130, 190, 212, 284, 336, 364, 424, 520, 622, 658, 772, 852, 894, 1026, 1118, 1262, 1462, 1566, 1620, 1732, 1790, 1910, 2344, 2472, 2670, 2738, 3088, 3160, 3382, 3610, 3766, 4006, 4252, 4336, 4766, 4854, 5034, 5126, 5690

Offset: 1

Author

Bruno Berselli, Apr 30 2011

Keywords

• nonn
• easy

Examples

			a(4) = 4*prime(4) - (prime(3) + prime(2) + prime(1)) = 4*7 - (5 + 3 + 2) = 18.
		

Links

• Bruno Berselli, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A152535, A166448.

Programs

Magma

[2] cat [n*NthPrime(n)-(&+[NthPrime(k): k in [1..n-1]]): n in [2..47]];

Mathematica

nn=50;Join[{2},With[{prs=Accumulate[Prime[Range[nn]]]},Table[n*Prime[n]-prs[[n-1]],{n,2,nn}]]] (* Harvey P. Dale, Nov 21 2014 *)

PARI

v=vector(10000);s=n=i=0;forprime(p=2,1e9,v[i++]=n++*p-s;if(i==#v,return,s+=p)) \\ Charles R Greathouse IV, May 01 2011

Formula

a(n) = A033286(n+1) - A007504(n) for n>1.