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 A086080 Number of 9's in decimal expansion of triangular number n(n+1)/2. 11
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,45 LINKS Antti Karttunen, Table of n, a(n) for n = 0..65537 [shifted by Georg Fischer, Apr 28 2021] PROG (PARI) A086080(n) = length(select(d -> (9==d), digits(binomial(n+1, 2)))); \\ Antti Karttunen, Sep 27 2018; corrected by Georg Fischer Apr 28 2021 CROSSREFS Cf. A000217. Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079. Sequence in context: A071164 A027345 A328959 * A281477 A070139 A116860 Adjacent sequences:  A086077 A086078 A086079 * A086081 A086082 A086083 KEYWORD base,nonn AUTHOR Jason Earls, Jul 08 2003 EXTENSIONS Zero at the beginning inserted by Antti Karttunen, Sep 27 2018 Zero at the beginning removed by Georg Fischer, Apr 28 2021 STATUS approved

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Last modified June 19 04:58 EDT 2021. Contains 345125 sequences. (Running on oeis4.)