A237589 - OEIS

%I #22 Jan 18 2022 02:40:39

%S 1,4,9,16,27,40,57,76,99,128,159,196,237,280,327,380,439,500,567,638,

%T 711,790,873,962,1059,1160,1263,1370,1479,1592,1719,1850,1987,2126,

%U 2275,2426,2583,2746,2913,3086,3265,3446,3637,3830,4027,4226,4437,4660,4887

%N Sum of first n odd noncomposite numbers.

%C Partial sums of A006005.

%F a(n) = A007504(n) - 1 = A014284(n+1) - 2.

%e For n = 5 the first five odd noncomposite numbers are 1, 3, 5, 7, 11, so a(5) = 1 + 3 + 5 + 7 + 11 = 27.

%p a := proc(n) option remember; `if`(n=1, 1, a(n-1) + ithprime(n)) end:

%p seq(a(n), n=1..49); # _Peter Luschny_, Sep 20 2018

%t a[1]=1; a[n_]:=a[n]=a[n-1]+Prime[n]; Table[a[n], {n,1,49}] (* _Robert P. P. McKone_, Jan 18 2022 *)

%o (PARI) terms(n) = my(s=1, i=0); forprime(p=3, , if(i >= n, break, print1(s, ", "); i++; s=s+p))

%o /* Print initial 50 terms as follows */

%o terms(50) \\ _Felix Fröhlich_, Sep 20 2018

%Y Cf. A000040, A006005, A007504, A008578, A014284.

%K nonn,easy

%O 1,2

%A _Omar E. Pol_, Feb 21 2014