login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A166380 Diagonal sums of exponential Riordan array [1+x^2*sec(x),x], A166378. 1
1, 3, 19, 223, 4667, 160045, 8207125, 587420875, 55869454855, 6809387511403, 1034264079708019, 191477762192490649, 42435372869814513769, 11090351278621719882899, 3374951549996881393302715 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..14.

FORMULA

a(n) = Sum_{k=0..n} C(n+k,2k)*A166377(k).

MATHEMATICA

(* The function RiordanArray is defined in A256893. *)

nmax = 14; R = RiordanArray[1 + #^2  Sec[#]&, #&, 2 nmax + 1, True];

a[n_] := Sum[R[[i, 2 n - i + 2]], {i, 2 n + 1, n + 1, -1}];

Table[a[n], {n, 0, nmax}] (* Jean-Fran├žois Alcover, Jul 20 2019 *)

CROSSREFS

Cf. A166377, A166378.

Sequence in context: A277407 A271587 A217906 * A136652 A136504 A003111

Adjacent sequences:  A166377 A166378 A166379 * A166381 A166382 A166383

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Oct 13 2009

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 December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)