1,2

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 121, p. 42, Ellipses, Paris 2008.

M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, p. 22.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

Eric Weisstein's World of Mathematics, Star Number

A007667 = 3*square star numbers (A006061) + 2.

a(n) = denominator of kappa(sqrt(6)/A054320(n)) where kappa(x) is the sum of successive remainders by computing the euclidean algorithm for (1, x). - Thomas Baruchel (baruchel(AT)users.sourceforge.net), Nov 29 2003

a(n) = 99(a(n-1) - a(n-2)) + a(n-3); a(n)=(5 - 2sqrt(6))/8*(sqrt(3) + sqrt(2))^(4n) + (5 + 2sqrt(6))/8*(sqrt(3) - sqrt(2))^(4n) - 1/4. - Ignacio Larrosa Canestro (ignacio.larrosa(AT)eresmas.net) Feb 27 2000

a(n) = 98*a(n-1) - a(n-2) + 24. - Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 14 2008

a(2)=121 because this is the 2nd star number (A003154) that is a square.

Digits := 1000:q := seq(floor(evalf(( (5+2*sqrt(6))^n*(sqrt(6)-2)-(5-2*sqrt(6))^n*(sqrt(6)+2))^2/16)), n=1..100);

A006061:=-(1+22*z+z**2)/(z-1)/(z**2-98*z+1); [Conjectured (correctly) by S. Plouffe in his 1992 dissertation.]

A007667 is 3*a(n)+2, sqrt(a(n)) is A054320. Cf. A003154.

Adjacent sequences: A006058 A006059 A006060 this_sequence A006062 A006063 A006064

Sequence in context: A006102 A036508 A054319 this_sequence A079215 A137466 A062689

nonn,easy

N. J. A. Sloane (njas(AT)research.att.com).

More terms from Eric Weisstein (eric(AT)weisstein.com) and Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 24 2002