A078571 Total number of prime factors of the average of n-th twin prime pair.
2, 2, 3, 3, 3, 3, 4, 5, 3, 5, 3, 4, 5, 7, 4, 4, 6, 5, 3, 5, 4, 5, 7, 4, 4, 4, 6, 3, 3, 5, 6, 3, 5, 4, 5, 5, 5, 5, 4, 5, 9, 4, 4, 4, 4, 6, 5, 5, 4, 6, 5, 7, 4, 3, 4, 4, 7, 3, 5, 5, 5, 5, 3, 6, 8, 4, 5, 3, 7, 5, 6, 3, 5, 9, 3, 9, 5, 5, 5, 3, 6, 7, 7, 8, 4, 4, 6, 5, 8, 4, 4, 3, 5, 7, 5, 3, 4, 7, 5, 5, 5, 3, 4, 4, 5
Offset: 1
Keywords
Examples
12th twin prime pair = (A001359(12), A006512(12)) = (149,151), hence A014574(12) = 150 = 2*3*5*5, therefore a(12) = 4. From _Robert G. Wilson v_, Aug 02 2010: (Start) 2) 4, 6 and no others < 10^9. 3) 12, 18, 30, 42, 102, 138, 282, 618, 642, 822, 1698, 1878, 2082, ... 4) 60, 150, 198, 228, 348, 462, 522, 570, 858, 1062, 1230, 1278, ... 5) 72, 108, 180, 270, 312, 420, 660, 828, 882, 1020, 1032, 1050, ... 6) 240, 600, 810, 1320, 1488, 2088, 2340, 2970, 3300, 4158, 4272, ... 7) 192, 432, 1620, 1872, 2268, 3000, 3120, 3528, 3672, 4050, 4128, ... 8) 2112, 3168, 3360, 5280, 7128, 7560, 9000, 12240, 13680, 16632, ... 9) 1152, 2592, 2688, 4800, 7488, 9720, 18048, 29760, 34848, 35280, ... 10) 14592, 21600, 22272, 29568, 32832, 33600, 64152, 71808, 75168, ... 11) 26112, 26880, 49920, 81648, 100800, 102912, 108288, 131712, ... 12) 15360, 23040, 58368, 95232, 133632, 134400, 196992, 219648, ... 13) 139968, 235008, 241920, 279552, 365568, 472392, 617472, 694272, ... 14) 138240, 202752, 345600, 684288, 724992, 783360, 817152, 875520, ... ... (End)
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Crossrefs
Programs
-
Mathematica
f[n_] := Plus @@ Last /@ FactorInteger@n; p = 3; lst = {}; While[p < 1000, If[ PrimeQ[p + 2], AppendTo[lst, f[p + 1]]]; p = NextPrime@p]: lst (* Robert G. Wilson v, Aug 02 2010 *)
Comments