A027208 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026725.

1, 4, 19, 72, 338, 1289, 6027, 23117, 107746, 415058, 1929383, 7456777, 34584731, 134005510, 620344059, 2408498148, 11131638368, 43289074671, 199800878749, 778025282080, 3586777011141, 13982303458588, 64394916131100, 251261623174835, 1156165698462868, 4514741175877259

Offset

1,2

Links

Table of n, a(n) for n=1..26.

Maple

A027208 := proc(n)
    add( A026725(n, k)*A026725(n, k+1), k=0..n-1) ;
end proc: # R. J. Mathar, Oct 21 2019

Crossrefs

Sequence in context: A219972 A284224 A268214 * A085348 A027232 A256714

Adjacent sequences: A027205 A027206 A027207 * A027209 A027210 A027211

Keyword

nonn

Author

Clark Kimberling

Extensions

Name corrected by R. J. Mathar, Oct 21 2019

More terms from Sean A. Irvine, Oct 24 2019

Status

approved