A356761 a(n) = L(2*L(n)) + L(2*L(n+1)), where L(n) is the n-th Lucas number (A000032).

10, 21, 65, 890, 40446, 33424885, 1322190707485, 44140596372269298846, 58360810951947188228658239895890, 2576080923024092500207469693559464507701547824744865, 150342171745412969401059031474740559845525757221446054521410222913066501974929718621

Offset

0,1

Links

Amiram Eldar, Table of n, a(n) for n = 0..15

Hideyuki Ohtsuka, Problem H-901, Advanced Problems and Solutions, The Fibonacci Quarterly, Vol. 60, No. 3 (2022), p. 281.

Formula

a(n) = A000032(2*A000032(n)) + A000032(2*A000032(n+1)).

Sum_{n>=0} (-1)^n/a(n) = 1/15 (Ohtsuka, 2022).

Mathematica

a[n_] := LucasL[2*LucasL[n]] + LucasL[2*LucasL[n + 1]]; Array[a, 11, 0]

Crossrefs

Cf. A000032, A356760.

Sequence in context: A045973 A095679 A095192 * A096564 A041196 A082669

Adjacent sequences: A356758 A356759 A356760 * A356762 A356763 A356764

Keyword

nonn

Author

Amiram Eldar, Aug 26 2022

Status

approved