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A256645 25-gonal pyramidal numbers: a(n) = n*(n+1)*(23*n-20)/6. 9
0, 1, 26, 98, 240, 475, 826, 1316, 1968, 2805, 3850, 5126, 6656, 8463, 10570, 13000, 15776, 18921, 22458, 26410, 30800, 35651, 40986, 46828, 53200, 60125, 67626, 75726, 84448, 93815, 103850, 114576, 126016, 138193, 151130, 164850, 179376, 194731, 210938 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

If b(n,k) = n*(n+1)*((k-2)*n-(k-5))/6 is n-th k-gonal pyramidal number, then b(n,k) = A000292(n) + (k-3)*A000292(n-1) (see Deza in References section, p. 96).

Also, b(n,k) = b(n,k-1) + A000292(n-1) (see Deza in References section, p. 95). Some examples:

for k=4, A000330(n) = A000292(n) + A000292(n-1);

for k=5, A002411(n) = A000330(n) + A000292(n-1);

for k=6, A002412(n) = A002411(n) + A000292(n-1), etc.

This is the case k=25.

REFERENCES

E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 93 (23rd row of the table).

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Index to sequences related to polygonal numbers

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

FORMULA

G.f.: x*(1 + 22*x)/(1 - x)^4.

a(n) = A000292(n) + 22*A000292(n-1) = A256716(n) + A000292(n-1), see comments.

a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4) for n>3. - Colin Barker, Apr 07 2015

MATHEMATICA

Table[n (n + 1) (23 n - 20)/6, {n, 0, 40}]

LinearRecurrence[{4, -6, 4, -1}, {0, 1, 26, 98}, 40] (* Vincenzo Librandi, Apr 08 2015 *)

PROG

(PARI) concat(0, Vec(x*(1 + 22*x)/(1 - x)^4 + O(x^100))) \\ Colin Barker, Apr 07 2015

(MAGMA) k:=25; [n*(n+1)*((k-2)*n-(k-5))/6: n in [0..40]]; // Vincenzo Librandi, Apr 08 2015

CROSSREFS

Partial sums of A255184.

Cf. similar sequences listed in A237616.

Cf. A000292, A256716.

Sequence in context: A038654 A010014 A095796 * A175549 A159541 A144129

Adjacent sequences:  A256642 A256643 A256644 * A256646 A256647 A256648

KEYWORD

nonn,easy

AUTHOR

Luciano Ancora, Apr 07 2015

STATUS

approved

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Last modified February 20 15:10 EST 2019. Contains 320337 sequences. (Running on oeis4.)