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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

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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 *)

CROSSREFS

Cf. A000796, A086639.

Sequence in context: A122791 A011429 A225409 * A011292 A021745 A190285

Adjacent sequences:  A083434 A083435 A083436 * A083438 A083439 A083440

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 February 19 10:03 EST 2020. Contains 332041 sequences. (Running on oeis4.)