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 A161595 The list of the A values in the common solutions to the 2 equations 15*k+1=A^2, 19*k+1=B^2. 4
 1, 16, 271, 4591, 77776, 1317601, 22321441, 378146896, 6406175791, 108526841551, 1838550130576, 31146825378241, 527657481299521, 8939030356713616, 151435858582831951, 2565470565551429551, 43461563755791470416, 736281113282903567521, 12473317362053569177441 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The 2 equations are equivalent to the Pell equation x^2- 285*y^2=1, with x=(285*k+17)/2 and y=A*B/2, case C=15 in A160682. Also: the first differences of A078366. Positive values of x (or y) satisfying x^2 - 17xy + y^2 + 15 = 0. - Colin Barker, Feb 14 2014 LINKS J.-C. Novelli, J.-Y. Thibon, Hopf Algebras of m-permutations,(m+1)-ary trees, and m-parking functions, arXiv preprint arXiv:1403.5962, 2014 Index entries for linear recurrences with constant coefficients, signature (17,-1). FORMULA A(t+2) = 17*A(t+1)-A(t). a(t) = ((285+15*w)*((17+w)/2)^(t-1)+(285-15*w)*((17-w)/2)^(t-1))/570, where w=sqrt(285). a(t) = ceiling of ((285+15*w)*((17+w)/2)^(t-1))/570. G.f.: x*(1-x)/(1-17*x+x^2). a(n) = 17*a(n-1)-a(n-2). - Colin Barker, Feb 14 2014 MAPLE t:=0: for a from 1 to 1000000 do b:=sqrt((19*a^2-4)/15): if (trunc(b)=b) then t:=t+1: n:=(a^2-1)/15: print(t, a, b, n): end if: end do: MATHEMATICA Rest[CoefficientList[Series[x (1-x)/(1-17x+x^2), {x, 0, 40}], x]] (* or *) LinearRecurrence[{17, -1}, {1, 16}, 20] (* Harvey P. Dale, Oct 12 2012 *) PROG (PARI) Vec(x*(1-x)/(1-17*x+x^2) + O(x^100)) \\ Colin Barker, Feb 14 2014 CROSSREFS Cf. A160682, A161599 (sequence of B), A161583 (sequence of k). Cf. similar sequences listed in A238379. Sequence in context: A166908 A221089 A119290 * A144660 A158574 A330151 Adjacent sequences: A161592 A161593 A161594 * A161596 A161597 A161598 KEYWORD nonn,easy AUTHOR Paul Weisenhorn, Jun 14 2009 EXTENSIONS Edited, extended by R. J. Mathar, Sep 02 2009 STATUS approved

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Last modified December 7 05:41 EST 2022. Contains 358649 sequences. (Running on oeis4.)