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A014771
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Squares of odd hexagonal numbers.
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0
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1, 225, 2025, 8281, 23409, 53361, 105625, 189225, 314721, 494209, 741321, 1071225, 1500625, 2047761, 2732409, 3575881, 4601025, 5832225, 7295401, 9018009, 11029041, 13359025, 16040025, 19105641, 22591009, 26532801
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| G.f.: x*(1+220*x+910*x^2+396*x^3+9*x^4)/(1-x)^5 [From Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
a(0)=1, a(1)=225, a(2)=2025, a(3)=8281, a(4)=23409, a(n)=5*a(n-1)- 10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5) [From Harvey P. Dale, June 23 2011]
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MATHEMATICA
| (Select[Table[n(2n-1), {n, 60}], OddQ])^2 (* or *) LinearRecurrence[ {5, -10, 10, -5, 1}, {1, 225, 2025, 8281, 23409}, 30] (* From Harvey P. Dale, June 23 2011 *)
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CROSSREFS
| Sequence in context: A076395 A203829 A105925 * A184878 A134741 A110204
Adjacent sequences: A014768 A014769 A014770 * A014772 A014773 A014774
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KEYWORD
| nonn,easy
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AUTHOR
| Mohammad K. Azarian (ma3(AT)evansville.edu)
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EXTENSIONS
| G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.
More terms from Erich Friedman (erich.friedman(AT)stetson.edu).
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