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A081323
a(n) = L(P(n)), where L = Lucas numbers A000032, P = Pell numbers A000129.
1
2, 1, 3, 11, 322, 1149851, 425730551631123, 208406472252232726621841472637412401, 18490864749804416780204061487408593066264011288598603441079481989361240762271783793922
OFFSET
0,1
FORMULA
a:= n-> (<<1|1>, <1|0>>^((<<2|1>, <1|0>>^n)[1, 2]). <<2, -1>>)[1, 1]:
seq(a(n), n=0..8); # Alois P. Heinz, Sep 19 2019
MATHEMATICA
l[n_] := l[n] = l[n - 1] + l[n - 2]; l[0] = 2; l[1] = 1; p[n_] := p[n] = 2p[n - 1] + p[n - 2]; p[0] = 0; p[1] = 1; Table[l[p[n]], {n, 0, 8}]
LucasL[LinearRecurrence[{2, 1}, {0, 1}, 10]] (* Harvey P. Dale, Sep 19 2019 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Mario Catalani (mario.catalani(AT)unito.it), Mar 18 2003
EXTENSIONS
Typo in a(8) corrected by Harvey P. Dale, Sep 19 2019
STATUS
approved