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A116596
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Number of partitions of n having exactly 1 part that appears exactly once.
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1
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1, 1, 1, 2, 4, 4, 8, 8, 12, 16, 23, 24, 40, 45, 59, 72, 99, 108, 153, 171, 224, 263, 341, 377, 504, 567, 711, 821, 1035, 1153, 1467, 1648, 2028, 2317, 2841, 3171, 3923, 4403, 5308, 6014, 7250, 8095, 9778, 10949, 13018, 14672, 17400, 19405, 23061, 25769, 30243
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| Column 1 of A116595.
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FORMULA
| G.f.=sum(x^j*(1-x^j)/(1-x^j+x^(2j)), j=1..infinity)product((1-x^j+x^(2j))/(1-x^j), j=1..infinity).
G.f. for number of partitions of n having exactly 1 part that appears exactly m times is sum(x^(m*j)*(1-x^j)/(1-x^(m*j)+x^((m+1)*j)), j=1..infinity)*product((1-x^(m*j)+x^((m+1)*j))/(1-x^j), j=1..infinity). - Vladeta Jovovic (vladeta(AT)eunet.rs), May 01 2006
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EXAMPLE
| a(5)=4 because we have [5],[3,1,1],[2,2,1] and [2,1,1,1] ([4,1],[3,2] and [1,1,1,1,1] do not qualify).
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MAPLE
| f:=sum(x^j*(1-x^j)/(1-x^j+x^(2*j)), j=1..75)*product((1-x^j+x^(2*j))/(1-x^j), j=1..75): fser:=series(f, x=0, 73): seq(coeff(fser, x^n), n=1..55);
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CROSSREFS
| Cf. A116595.
Sequence in context: A140513 A188112 A166632 * A048656 A107848 A188824
Adjacent sequences: A116593 A116594 A116595 * A116597 A116598 A116599
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KEYWORD
| nonn
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AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 18 2006
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