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A248956
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Number of polynomials a_k*x^k + ... + a_1*x + a_0 with k > 0, integer coefficients and only non-multiple positive integer roots and a_0 = p^n (p is a prime).
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3
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1, 3, 5, 9, 13, 19, 27, 37, 49, 65, 85, 109, 139, 175, 219, 273, 337, 413, 505, 613, 741, 893, 1071, 1279, 1523, 1807, 2137, 2521, 2965, 3477, 4069, 4749, 5529, 6425, 7449, 8619, 9955, 11475, 13203, 15167, 17393, 19913, 22765, 25985, 29617, 33713, 38321, 43501
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OFFSET
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0,2
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COMMENTS
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If D_n = {p^0, ..., p^n} is the set of all positive divisors of p^n (p is a prime), then a(n) gives the number of all subsets of D_n for which the product of all their elements is a divisor of p^n. Furthermore, a(n) gives the number of all strict partitions of n including the integer 0.
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LINKS
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FORMULA
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a(n) = -1 + 2*Sum_{k=0..n} a*(k) where a*(n) = A000009(n).
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EXAMPLE
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a(1) = 3: -p*x+p; -x+p; x^2 - (p+1)*x + p.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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