login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A275331 Triangle read by rows, T(n,k) = k*Sum_{m=1..n/k} t(k)*t(n-k*m+1) with t = A000081, for n>=1 and 1<=k<=n. 1
1, 2, 2, 4, 2, 6, 8, 6, 6, 16, 17, 10, 12, 16, 45, 37, 24, 30, 32, 45, 120, 85, 50, 60, 64, 90, 120, 336, 200, 120, 132, 160, 180, 240, 336, 920, 486, 280, 318, 336, 405, 480, 672, 920, 2574, 1205, 692, 750, 800, 945, 1080, 1344, 1840, 2574, 7190 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

Triangle starts:

[n] [k=1,2,...] row sum

[1] [1] 1

[2] [2, 2] 4

[3] [4, 2, 6] 12

[4] [8, 6, 6, 16] 36

[5] [17, 10, 12, 16, 45] 100

[6] [37, 24, 30, 32, 45, 120] 288

[7] [85, 50, 60, 64, 90, 120, 336] 805

[8] [200, 120, 132, 160, 180, 240, 336, 920] 2288

[9] [486, 280, 318, 336, 405, 480, 672, 920, 2574] 6471

PROG

(Sage)

@cached_function

def t():

    n = 1

    b = [0, 1]

    while True:

        S = [k*sum(b[k]*b[n-k*m+1] for m in (1..n//k)) for k in (1..n)]

        b.append(sum(S)//n)

        yield S

        n += 1

t_list = t()

for n in (1..8): print(next(t_list))

CROSSREFS

T(n,0) = A087803(n).

T(n,n) = A055544(n).

Sum_k T(n,k) = A095350(n+1).

Cf. A000081, A275330.

Sequence in context: A307536 A248842 A286538 * A308828 A325683 A331121

Adjacent sequences:  A275328 A275329 A275330 * A275332 A275333 A275334

KEYWORD

nonn,tabl

AUTHOR

Peter Luschny, Aug 18 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 31 04:43 EDT 2020. Contains 334747 sequences. (Running on oeis4.)