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 A160922 Numbers k such that A000217(k)/A006218(k) is an integer. 1
 1, 2, 47, 347, 348, 6930, 6947, 6948, 69269, 379131, 4011952, 8280003 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The next term, if it exists, is > 10^9. - Vaclav Kotesovec, Oct 16 2018 The next term, if it exists, is > 10^10. - Charles R Greathouse IV, Nov 05 2021 LINKS Table of n, a(n) for n=1..12. PROG (PARI) is(n)=my(m=sum(k=1, sqrtint(n), n\k)*2-sqrtint(n)^2); n^2%m==0 \\ Charles R Greathouse IV, Nov 04 2021 (PARI) A006218(n)=sum(k=1, sqrtint(n), n\k)*2-sqrtint(n)^2 list(lim, startAt=1)=startAt=ceil(startAt); my(v=List(), s=A006218(startAt-1)); for(n=startAt, lim, s+=numdiv(n); if(binomial(n+1, 2)%s==0, listput(v, n))); Vec(v) \\ Charles R Greathouse IV, Nov 04 2021 CROSSREFS Cf. A000217, A006218, A000005. Sequence in context: A304725 A128822 A226420 * A276509 A120050 A112783 Adjacent sequences: A160919 A160920 A160921 * A160923 A160924 A160925 KEYWORD more,nonn AUTHOR Ctibor O. Zizka, May 30 2009 EXTENSIONS a(9)-a(10) from R. J. Mathar, Aug 30 2010 a(11) from Paolo P. Lava, May 06 2015 a(12) from Vaclav Kotesovec, Oct 14 2018 STATUS approved

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Last modified April 14 04:54 EDT 2024. Contains 371655 sequences. (Running on oeis4.)