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A083437 Write decimal expansion of Pi in triangular form; sequence gives right edge. 4
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; text; internal format)
OFFSET
1,1
COMMENTS
Select digits from decimal expansion of Pi corresponding to triangular number indices. [From Harvey P. Dale, Oct 15 2011]
LINKS
FORMULA
a(n)=A000796(2-n(n+1)/2). - M. F. Hasler, Oct 20 2011
EXAMPLE
Triangle is
3
14
159
2653
58979
323846
2643383
27950288
419716939
9375105820
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]]]]] (* Harvey P. Dale, Oct 15 2011 *)
Module[{nn=110}, Last[#]&/@TakeList[RealDigits[Pi, 10, (nn(nn+1))/2][[1]], Range[ nn]]] (* Harvey P. Dale, Oct 02 2022 *)
CROSSREFS
Sequence in context: A122791 A011429 A225409 * A011292 A021745 A190285
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Jul 24 2003
EXTENSIONS
Edited by Robert G. Wilson v, Jul 26 2003
STATUS
approved

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Last modified June 14 12:17 EDT 2024. Contains 373400 sequences. (Running on oeis4.)