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Search: id:A113632
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| A113632 |
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1 + 2*n + 3*n^2 + 4*n^3 + 5*n^4 + 6*n^5 + 7*n^6 + 8*n^7 + 9*n^8 + 10*n^9. |
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+0
2
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| 1, 55, 9217, 280483, 3378745, 23803711, 118513705, 462945547, 1512003793, 4303999495, 10987654321, 25678050355, 55776799177, 113924725903, 220792014745, 408951042331, 728121033505, 1252121211607, 2087920281313
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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1 + 2x + 3x^2 + 4x^3 + 5x^4 + 6x^5 + 7*x^6 + 8*x^7 + 9*x^8 + 10*x^9 is the derivative of 1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + x^9 + x^10 = (x^11 - 1)/(x-1).
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FORMULA
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a(n) = 1 + 2*n + 3*n^2 + 4*n^3 + 5*n^4 + 6*n^5 + 7*n^6 + 8*n^7 + 9*n^8 + 10*n^9.
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EXAMPLE
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a(5) = 1 + 2*5 + 3*5^2 + 4*5^3 + 5*5^4 + 6*5^5 + 7*5^6 + 8*5^7 + 9*5^8 + 10*5^9 = 23803711 is prime.
a(30) = 1 + 2*30 + 3*30^2 + 4*30^3 + 5*30^4 + 6*30^5 + 7*30^6 + 8*30^7 + 9*30^8 + 10*30^9 = 202915112960761 is prime.
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CROSSREFS
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Cf. A000012, A005408, A056109, A056578, A056579.
Sequence in context: A090813 A145617 A105842 this_sequence A163036 A033512 A027580
Adjacent sequences: A113629 A113630 A113631 this_sequence A113633 A113634 A113635
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Jan 14 2006
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