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 A225748 #5 May 14 2013 13:56:42 %S A225748 2,4,12,16,22,38,48,52,64,66,67,90,93,132,148,149,155,163,165,185,201, %T A225748 208,222,229,230,237,242,264,268,275,289,309,324,332,339,351,352,359, %U A225748 362,363,373,382,384,401,403,465,471,474,485,507,517,518,528,532 %N A225748 Numbers n for which the sum of the numbers in the Collatz (3x+1) iteration of n is prime. %e A225748 12 is a member since 12 + 6 + 3 + 10 + 5 + 16 + 8 + 4 + 2 + 1 = 67 is a prime. %t A225748 coll[n_]:=NestWhileList[If[EvenQ[#],#/2,3#+1] &,n,#>1 &]; Select[Range[500],PrimeQ[Total[coll[#]]] &] %Y A225748 Cf. A033493. %K A225748 nonn %O A225748 1,1 %A A225748 _Jayanta Basu_, May 14 2013