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 A273189 a(n) is the third number in a triple consisting of 3 numbers, which when squared are part of a right diagonal of a magic square of squares. 3
 51, 401, 2451, 14401, 84051, 490001, 2856051, 16646401, 97022451, 565488401, 3295908051, 19209960001, 111963852051, 652573152401, 3803475062451, 22168277222401, 129206188272051, 753068852410001, 4389206926188051, 25582172704718401, 149103829302122451 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The multiplying factor 6 (in the recursion formulas below) appears to come from the ratio of b(1)/b(0) of the sequence. Each of the lines of tables (V vs VII) or (VI vs VIII) in oddwheel.com/ImaginaryB.html generates this factor. k is obtained from the difference of the offsets of two relate sequences. this one, (II), starting at 51 and a second, (I), at 99 (to be submitted separately). Thus, k =[Ic(n)- IIc(n)]*2. When n=0, Ic(0)=99 and IIc(0)=51 giving the value for k of (99-51)*2=96. Furthermore, k is the same constant number for any value of n. The differences between number in the sequence are identical in both of the related sequences. LINKS Colin Barker, Table of n, a(n) for n = 0..1000 E. Gutierrez, Table of Tuples for Square of Squares (Part IC) Index entries for linear recurrences with constant coefficients, signature (7,-7,1). FORMULA a(0)= 51, a(1)= 401, a(n+1)= a(n)*6 - a(n-1) + k where k=96. From Colin Barker, May 18 2016: (Start) a(n) = (-24+25/2*(3-2*sqrt(2))^(1+n)+25/2*(3+2*sqrt(2))^(1+n)). a(n) = 7*a(n-1)-7*a(n-2)+a(n-3) for n>2. G.f.: (51+44*x+x^2) / ((1-x)*(1-6*x+x^2)). (End) EXAMPLE a(2)= 401*6 - (51 - 96)= 2451; a(3)= 2451*6 - (401 - 96)= 14401; a(4)= 14401*6 - (2451 - 96)= 84051. MATHEMATICA CoefficientList[Series[(51 + 44 x + x^2)/((1 - x) (1 - 6 x + x^2)), {x, 0, 20}], x] (* Michael De Vlieger, May 18 2016 *) LinearRecurrence[{7, -7, 1}, {51, 401, 2451}, 30] (* Harvey P. Dale, Feb 21 2020 *) PROG (PARI) Vec((51+44*x+x^2)/((1-x)*(1-6*x+x^2)) + O(x^50)) \\ Colin Barker, May 18 2016 CROSSREFS Cf. A178218, A273182, A273187. Sequence in context: A165087 A152579 A083669 * A222910 A259692 A204215 Adjacent sequences:  A273186 A273187 A273188 * A273190 A273191 A273192 KEYWORD nonn,easy AUTHOR Eddie Gutierrez, May 17 2016 EXTENSIONS More terms from Colin Barker, May 18 2016 STATUS approved

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Last modified August 8 05:50 EDT 2020. Contains 336290 sequences. (Running on oeis4.)