|
|
A015508
|
|
a(1) = 1, a(n) = Sum_{k=1..n-1} ((7^k - 1)/6)*a(k).
|
|
10
|
|
|
1, 1, 9, 522, 209322, 586520244, 11501075464596, 1578614616119517768, 1516734501782248791012168, 10200952598655696033329019125136, 480252779391204632593567857157274897424, 158269444415262012661462389451687149577571916192
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
a[n_, m_]:= a[n, m]= If[n<3, 1, (m^(n-1) + m-2)*a[n-1, m]/(m-1)];
|
|
PROG
|
(Magma) [n le 2 select 1 else ((7^(n-1) + 5)/6)*Self(n-1): n in [1..15]]; // Vincenzo Librandi, Nov 12 2012
(SageMath)
def a(n, m): return 1 if (n<3) else (m^(n-1)+m-2)*a(n-1, m)/(m-1)
|
|
CROSSREFS
|
Sequences with the recurrence a(n) = (m^(n-1) + m-2)*a(n-1)/(m-1): A036442 (m=2), A015502 (m=3), A015503 (m=4), A015506 (m=5), A015507 (m=6), this sequence (m=7), A015509 (m=8), A015511 (m=9), A015512 (m=10), A015513 (m=11), A015515 (m=12).
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|