A047673 - OEIS

A047673

Row 4 of square array defined in A047671.

1, 13, 61, 193, 481, 1021, 1933, 3361, 5473, 8461, 12541, 17953, 24961, 33853, 44941, 58561, 75073, 94861, 118333, 145921, 178081, 215293, 258061, 306913, 362401, 425101, 495613, 574561, 662593, 760381, 868621, 988033, 1119361, 1263373, 1420861, 1592641, 1779553

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..37.

Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

FORMULA

a(n) = n^4 - 2*n^3 + 5*n^2 - 4*n + 1.

From Elmo R. Oliveira, Aug 30 2025: (Start)

G.f.: -x*(1 + 8*x + 6*x^2 + 8*x^3 + x^4)/(x-1)^5.

E.g.f.: -1 + (1 + 6*x^2 + 4*x^3 + x^4)*exp(x).

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n > 5. (End)