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(Ruby)
def s(k, m, n)
s = 0
(1..n).each{|i| s += i if n % i == 0 && i % k == m}
s
end
def A109091(n)
(1..n).map{|i| s(5, 1, i) + s(5, 4, i) - s(5, 2, i) - s(5, 3, i)}
end # Seiichi Manyama, Apr 01 2017
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Watson, G. N.; Ramanujans Vermutung ueber Zerfaellungsanzahlen. J. Reine Angew. Math. (Crelle), 179 (1938), 97-128. This is the expression B^5/C in the notation of p. 106. [Added by N. J. A. Sloane, Nov 13 2009]
G. N. Watson, <a href="http://www.digizeitschriften.de/dms/img/?PID=GDZPPN002174499&physid=phys107
GDZ, <a href="http://gdz.sub.uni-goettingen.de/no_cache/dms/load/toc/?IDDOC=238618">Digitized volumes of Crelle</a> [Added by N. J. A. Sloane, Nov 13 2009]
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Seiichi Manyama, <a href="/A109091/b109091_1.txt">Table of n, a(n) for n = 1..10000</a>
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