This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A079090 #14 Apr 07 2025 09:51:41 %S A079090 3,5,5,5,12,10,10,10,10,10,21,29,23,16,5,10,41,50,22,42,44,17,17,15, %T A079090 27,35,18,21,38,24,16,39,40,17,29,100,122,53,41,39,30,25,102,111,21, %U A079090 60,62,31,52,44,23,21,23,55,59,21,27,158,189,123,83,23,36,175,213,141,98,47 %N A079090 Sum of distinct prime factors of (prime(n)+1)*(prime(n+1)+1)/4. %H A079090 Reinhard Zumkeller, <a href="/A079090/b079090.txt">Table of n, a(n) for n = 1..10000</a> %F A079090 a(n) = A008472(A079079(n)). %t A079090 Total[Transpose[FactorInteger[((#[[1]]+1)(#[[2]]+1))/4]][[1]]]&/@ Partition[Prime[Range[70]],2,1] (* _Harvey P. Dale_, Apr 24 2015 *) %o A079090 (Haskell) %o A079090 a079090 = a008472 . a079079 -- _Reinhard Zumkeller_, Oct 09 2012 %o A079090 (PARI) a(n) = vecsum(factor((prime(n)+1)*(prime(n+1)+1)/4)[, 1]); \\ _Amiram Eldar_, Apr 07 2025 %Y A079090 Cf. A008472, A079079, A079085, A079089, A079091. %K A079090 nonn %O A079090 1,1 %A A079090 _Reinhard Zumkeller_, Dec 22 2002