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Search: id:A113630
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| A113630 |
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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. |
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+0
4
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| 1, 45, 4097, 83653, 757305, 4272461, 17736745, 59409477, 169826513, 429794605, 987654321, 2098573445, 4178995657, 7879732173, 14181546905, 24517448581, 40926266145, 66242446637, 104327377633, 160347899205, 241108033241
(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 is the derivative of 1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + x^9 = (x^10 - 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.
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EXAMPLE
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a(3) = 1 + 2*3 + 3*3^2 + 4*3^3 + 5*3^4 + 6*3^5 + 7*3^6 + 8*3^7 + 9*3^8 = 83653 is prime.
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 = 4272461 is prime.
a(8) = 1 + 2*8 + 3*8^2 + 4*8^3 + 5*8^4 + 6*8^5 + 7*8^6 + 8*8^7 + 9*8^8 = 169826513 is prime.
a(23) = 1 + 2*23 + 3*23^2 + 4*23^3 + 5*23^4 + 6*23^5 + 7*23^6 + 8*23^7 + 9*23^8 = 733113789893 is prime.
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CROSSREFS
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Cf. A000012, A005408, A056109, A056578, A056579.
Adjacent sequences: A113627 A113628 A113629 this_sequence A113631 A113632 A113633
Sequence in context: A035097 A130017 A025755 this_sequence A143004 A004707 A036521
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Jan 14 2006
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