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A139172
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Natural numbers of the form (n!-2)/2.
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9
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0, 2, 11, 59, 359, 2519, 20159, 181439, 1814399, 19958399, 239500799, 3113510399, 43589145599, 653837183999, 10461394943999, 177843714047999, 3201186852863999, 60822550204415999, 1216451004088319999
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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COMMENTS
| Natural numbers of the form (n!-m)/m :
for m=1 n!-1 see A033312
for m=2 (n!-2)/2 see A139172
for m=3 (n!-3)/3 see A139173
for m=4 (n!-4)/4 see A139174
for m=5 (n!-5)/5 see A139175
for m=6 (n!-6)/6 see A139176
for m=7 (n!-7)/7 see A139177
for m=8 (n!-8)/8 see A139183
for m=9 (n!-9)/9 see A139184
for m=10 (n!-10)/10 see A139185
Contribution from Artur Jasinski, Oct 14 2008: (Start)
a(n) = Number of numbers removed in first step of Eratosthenes' sieve for n!
a(5)=A145532(1) a(6)=A145533(1) a(7)=A145534(1) a(8)=A145535(1) a(9)=A145536(1) a(10)=A145537(1) (End)
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 2..300
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MATHEMATICA
| Table[(n! - 2)/2, {n, 2, 20}]
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PROG
| (MAGMA) [(Factorial(n)-2)/2: n in [2..25]]; // Vincenzo Librandi, Jul 20 2011
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CROSSREFS
| Cf. A033312, A139172, A139173, A139174, A139175, A139176, A139177, A139183, A139184.
Sequence in context: A162771 A020057 A054564 * A164034 A074615 A126034
Adjacent sequences: A139169 A139170 A139171 * A139173 A139174 A139175
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KEYWORD
| nonn,easy
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Apr 11 2008
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