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 A216853 18k^2-12k-7 interleaved with 18k^2+6k+5 for k>=0. 0
 -7, 5, -1, 29, 41, 89, 119, 185, 233, 317, 383, 485, 569, 689, 791, 929, 1049, 1205, 1343, 1517, 1673, 1865, 2039, 2249, 2441, 2669, 2879, 3125, 3353, 3617, 3863, 4145, 4409, 4709, 4991, 5309, 5609, 5945, 6263, 6617, 6953, 7325, 7679, 8069, 8441, 8849 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The sequence (the third in the family) is present as a family of single interleaved sequence of which there are many which are separated or factored out to give individual sequences. The larger sequence produces two smaller interleaved sequences where one of them  has the formulas above and the other interleaved sequence has the formulas (18n^2-24n-1) and  (18n^2-6n+5). The latter interleaved sequence is A214493. There are three sequences in this family. LINKS Eddie Gutierrez New Interleaved Sequences Part B  on oddwheel.com, Section B1 Line No. 22 (square_sequencesII.html) Part B Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1). FORMULA G.f.: -(7-19*x+11*x^2-17*x^3)/((1+x)*(1-x)^3). - Bruno Berselli, Oct 05 2012 a(n) = (6*n*(3*n-4)-27*(-1)^n-1)/4. - Bruno Berselli, Oct 05 2012 MATHEMATICA Flatten[Table[{18 n^2 - 12 n - 7, 18 n^2 + 6 n + 5}, {n, 0, 22}]] (* Bruno Berselli, Oct 05 2012 *) PROG (MAGMA) &cat[[18*k^2-12*k-7, 18*k^2+6*k+5]: k in [0..22]]; // Bruno Berselli, Oct 05 2012 (PARI) vector(46, n, k=(n-1)\2; if(n%2, 18*k^2-12*k-7, 18*k^2+6*k+5)) \\ Bruno Berselli, Oct 05 2012 CROSSREFS Cf. A178218, A214345, A214393, A214405, A216876. Sequence in context: A323811 A316334 A196486 * A084911 A272169 A073742 Adjacent sequences:  A216850 A216851 A216852 * A216854 A216855 A216856 KEYWORD sign,easy AUTHOR Eddie Gutierrez, Sep 17 2012 EXTENSIONS Definition rewritten by Bruno Berselli, Oct 25 2012 STATUS approved

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Last modified January 24 22:09 EST 2021. Contains 340414 sequences. (Running on oeis4.)