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URL: https://oeis.org/A047661

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A047661
Row 5 of square array defined in A047662.
1
5, 30, 115, 340, 841, 1826, 3591, 6536, 11181, 18182, 28347, 42652, 62257, 88522, 123023, 167568, 224213, 295278, 383363, 491364, 622489, 780274, 968599, 1191704, 1454205, 1761110, 2117835, 2530220, 3004545, 3547546, 4166431, 4868896, 5663141, 6557886, 7562387
OFFSET
1,1
FORMULA
a(n) = (n/15)*(2*n^4 + 5*n^3 + 20*n^2 + 25*n + 23). [Corrected by Sean A. Irvine, May 13 2021]
From Elmo R. Oliveira, Sep 02 2025: (Start)
G.f.: x*(5 + 10*x^2 + x^4)/(x-1)^6.
E.g.f.: x*(5 + 5*x + x^2)*(15 + 15*x + 2*x^2)*exp(x)/15.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n > 6. (End)
MATHEMATICA
Table[(n/15)(2n^4+5n^3+20n^2+25n+23), {n, 30}] (* Harvey P. Dale, Nov 25 2022 *)
PROG
(PARI) my(x='x+O('x^35)); Vec(x*(5+10*x^2+x^4)/(1-x)^6) \\ Elmo R. Oliveira, Sep 02 2025
CROSSREFS
Cf. A047662.
Sequence in context: A062990 A018213 A359975 * A000649 A027173 A286973
KEYWORD
nonn,easy
EXTENSIONS
More terms from Elmo R. Oliveira, Sep 02 2025
STATUS
approved