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A168128
Numbers Sum_(j=1..k) sigma(j) / sigma(k) when this expression is an integer.
3
1, 2, 23, 247, 699, 55921, 70936, 152730, 478017, 4879815, 12909834588, 223070292558, 583407686653, 601718433498
OFFSET
1,2
COMMENTS
Numbers A024916(k)/A000203(k) when it is an integer.
Corresponding values of k, sigma(k) and Sum_(j=1..k) sigma(j) are given in A168127, A168129 and A168130. - Jaroslav Krizek, Nov 21 2009
EXAMPLE
a(3)=23 because A024916(29) / A000203(29) = 690 / 30 = 23 is an integer, where 29 is A168127(3).
PROG
(PARI) m=0; for(k=1, 11413204, s=sigma(k); m=m+s; if(m%s==0, print1(m/s ", "))) \\ Donovan Johnson, Oct 16 2013
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jaroslav Krizek, Nov 18 2009, Dec 04 2009
EXTENSIONS
a(8)-a(10) from Donovan Johnson, Oct 16 2013
a(11)-a(14) from Giovanni Resta, Jun 06 2016
Name edited by Michel Marcus, Feb 22 2020
STATUS
approved