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A334082 a(n) is the number of binomial coefficients C(n,k), with 0<=k<=n, that are not practical. 2
0, 0, 2, 0, 4, 2, 6, 1, 2, 4, 6, 2, 8, 10, 14, 0, 6, 2, 8, 5, 10, 10, 20, 2, 8, 14, 14, 6, 16, 14, 30, 0, 2, 4, 6, 2, 6, 10, 16, 4, 10, 10, 24, 16, 14, 20, 36, 4, 8, 10, 16, 12, 30, 14, 30, 6, 14, 18, 34, 14, 34, 38, 62, 0, 2, 2, 6, 10, 12, 10, 24, 2, 8, 14, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..75.

Paolo Leonetti, Carlo Sanna, Practical numbers among the binomial coefficients, arXiv:1905.12023 [math.NT], 2019.

PROG

(PARI) a(n) = sum(k=0, n, !is_A005153(binomial(n, k)));

CROSSREFS

Cf. A005153 (practical numbers), A007318 (binomial coefficients).

Cf. A334083, A334084.

Sequence in context: A153733 A083218 A203908 * A307704 A139716 A168232

Adjacent sequences:  A334079 A334080 A334081 * A334083 A334084 A334085

KEYWORD

nonn

AUTHOR

Michel Marcus, Apr 14 2020

STATUS

approved

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Last modified April 22 21:05 EDT 2021. Contains 343177 sequences. (Running on oeis4.)