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A083437
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Write decimal expansion of Pi in triangular form; sequence gives right edge.
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4
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3, 4, 9, 3, 9, 6, 3, 8, 9, 0, 0, 0, 5, 4, 4, 2, 8, 3, 8, 7, 3, 5, 2, 7, 1, 6, 6, 7, 3, 4, 1, 9, 7, 9, 4, 5, 2, 7, 5, 2, 3, 9, 1, 0, 8, 1, 3, 0, 0, 4, 6, 3, 2, 2, 1, 9, 6, 6, 5, 6, 2, 6, 6, 0, 9, 4, 6, 1, 6, 3, 4, 8, 4, 3, 1, 8, 6, 2, 2, 5, 7, 2, 5, 5, 9, 5, 9, 6, 5, 1, 6, 5, 5, 3, 1, 6, 8, 6, 3, 2, 2, 9, 7, 1, 6
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Select digits from decimal expansion of Pi corresponding to triangular number indices. [From Harvey P. Dale, Oct 15 2011]
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LINKS
| Harvey P. Dale, Table of n, a(n) for n = 1..1000
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FORMULA
| a(n)=A000796(2-n(n+1)/2). - M. F. Hasler, Oct 20 2011
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EXAMPLE
| Triangle is
3
14
159
2653
58979
323846
2643383
27950288
419716939
9375105820
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MATHEMATICA
| pi = RealDigits[Pi, 10, 5565][[1]]; Table[ pi[[n(n + 1)/2]], {n, 1, 105}]
With[{nn=110}, RealDigits[Pi, 10, (nn(nn+1))/2][[1]][[Accumulate[ Range[ nn]]]]] (* From Harvey P. Dale, Oct 15 2011 *)
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CROSSREFS
| Cf. A000796, A086639.
Sequence in context: A019900 A122791 A011429 * A011292 A021745 A190285
Adjacent sequences: A083434 A083435 A083436 * A083438 A083439 A083440
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KEYWORD
| easy,nonn,base
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AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Jul 24 2003
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 26 2003
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