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A343457
a(n) = A343376(A343456(n)+1) for n >= 1.
5
1, 1, 2, 94, 1504, 47, 2021, 3827, 110983, 24041312968, 23771185856, 2254245120986320, 3159913332429749280, 15303008852766928656, 30074663231479450067, 54935894063396493508795283474555648601078162, 133235460924631191149173867066238838540248070798, 29749639147063441320702404607288534736145087754344
OFFSET
1,3
COMMENTS
Subsequence of A343376.
LINKS
Michael De Vlieger, Annotated log-log scatterplot of A343376(n) for 1..120 indicating n in this sequence in red.
EXAMPLE
a(1) = A343376(A343456(1)+1) = A343376(2) = 1.
a(2) = A343376(A343456(2)+1) = A343376(6) = 1.
a(3) = A343376(A343456(3)+1) = A343376(11) = 2.
a(4) = A343376(A343456(4)+1) = A343376(23) = 94.
a(5) = A343376(A343456(5)+1) = A343376(32) = 1504.
MAPLE
a:= proc(n) option remember; local q; `if`(n<2, n,
`if`(irem(a(n-1), n-1, 'q')=0, q, a(n-1)+a(n-2)))
end:
q:= n-> is(a(n+1)=a(n)/n):
map(x-> a(x+1), select(q, [$1..300]))[]; # Alois P. Heinz, Apr 23 2021
MATHEMATICA
Block[{a = {0, 1}, b = {}}, Do[If[Mod[#, i] == 0, AppendTo[a, #/i]; AppendTo[b, i], AppendTo[a, # + a[[-2]] ]] &@ a[[-1]], {i, 300}]; a[[b + 2]] ] (* Michael De Vlieger, Apr 22 2021 *)
PROG
(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, if (va[n-1] % (n-1), va[n] = va[n-1] + va[n-2], va[n] = va[n-1]/(n-1)); ); va; } \\ A343376
listk(nn) = {my(va = lista(nn)); for (k=1, nn-1, if (va[k]/k == va[k+1], print1(va[k]/k, ", ")); ); } \\ Michel Marcus, Apr 20 2021
CROSSREFS
Sequence in context: A287611 A363017 A158980 * A220970 A302577 A346654
KEYWORD
nonn
AUTHOR
Timothy L. Tiffin, Apr 15 2021
STATUS
approved