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A151611 a(1) = 4; for n >= 1, a(n+1) = 4 + binomial(a(n), 2). 1
4, 10, 49, 1180, 695614, 241939070695, 29267256964259134356169, 428286165105987400438217763289707431507000200 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Arises in a geometry problem: see link.
Next term (a(9)) has 89 digits. - Emeric Deutsch, Jun 20 2009
LINKS
Antreas P. Hatzipolakis, Concurrent NPC's.
Antreas P. Hatzipolakis, Concurrent NPCs, digest of 4 messages in Anopolis Yahoo group, May 23, 2009 - Aug 26, 2016. [Cached copy]
MAPLE
a[1] := 4: for n to 7 do a[n+1] := 4+binomial(a[n], 2) end do: seq(a[n], n = 1 .. 8); # Emeric Deutsch, Jun 20 2009
PROG
(Magma) [n eq 1 select 4 else 4+Binomial(Self(n-1), 2):n in [1..8]]; // Marius A. Burtea, Nov 16 2019
CROSSREFS
Sequence in context: A364281 A173086 A081565 * A351046 A208236 A032495
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 28 2009
EXTENSIONS
More terms from Emeric Deutsch, Jun 20 2009
STATUS
approved

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Last modified July 22 06:32 EDT 2024. Contains 374481 sequences. (Running on oeis4.)