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A156798 n^4 + 5*n^2 + 4. 4
4, 10, 40, 130, 340, 754, 1480, 2650, 4420, 6970, 10504, 15250, 21460, 29410, 39400, 51754, 66820, 84970, 106600, 132130, 162004, 196690, 236680, 282490, 334660, 393754, 460360, 535090, 618580, 711490, 814504, 928330, 1053700, 1191370 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

a(n) = A002522(n)*A087475(n) = A000290(n)+A000290(A059100(n)) = A028552(A002522(n)).

LINKS

Table of n, a(n) for n=0..33.

FORMULA

(n^2 + 1)*(n^2 + 4) = n^2 + (n^2 + 2)^2.

G.f.: 2*(2-5*x+15*x^2-5*x^3+5*x^4)/(1-x)^5 [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009]

a(0)=4, a(1)=10, a(2)=40, a(3)=130, a(4)=340, a(n)=5a(n-1)- 10a(n-2)+ 10a(n-3)-5a(n-4)+a(n-5) [From Harvey P. Dale, May 04 2011]

MATHEMATICA

Table[n^4+5n^2+4, {n, 0, 40}]

PROG

(MAGMA)[n^4+5*n^2+4: n in [0..50]]

(PARI) a(n)=n^4+5*n^2+4

CROSSREFS

Sequence in context: A149205 A149206 A149207 * A149208 A149209 A053792

Adjacent sequences:  A156795 A156796 A156797 * A156799 A156800 A156801

KEYWORD

nonn,easy

AUTHOR

Reinhard Zumkeller, Feb 16 2009

EXTENSIONS

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.

STATUS

approved

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Last modified October 20 17:39 EDT 2017. Contains 293648 sequences.