This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A006242 Extracting a square root. (Formerly M4758) 3
 10, 970, 912670090, 760223786832147978143718730, 439363892017598816969702791108195858981800447259539613873486126455827777484460810 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Jeffrey Shallit, personal communication. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..7 E. B. Escott, Rapid method for extracting a square root, Amer. Math. Monthly, 44 (1937), 644-646. FORMULA a(1) = 10, a(n) = a(n-1)^3 - 3*a(n-1) [From Escott]. - Sean A. Irvine, Feb 08 2017 a(n) = (5 + 2*sqrt(6))^(3^(n-1)) + (5 - 2*sqrt(6))^(3^(n-1)). - Bruno Berselli, Feb 10 2017 MATHEMATICA RecurrenceTable[{a[1]==10, a[n]==a[n-1]^3 - 3 a[n-1]}, a, {n, 8}] (* Vincenzo Librandi, Feb 09 2017 *) PROG (MAGMA) [n eq 1 select 10 else Self(n-1)^3-3*Self(n-1): n in [1..5]]; // Vincenzo Librandi, Feb 09 2017 CROSSREFS Cf. A006243. Sequence in context: A194791 A292669 A159869 * A163566 A168520 A200993 Adjacent sequences:  A006239 A006240 A006241 * A006243 A006244 A006245 KEYWORD nonn,changed AUTHOR EXTENSIONS New offset and a(5) from Sean A. Irvine, Feb 08 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.