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A106588
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Difference between n-th prime squared and n-th perfect square.
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0
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3, 5, 16, 33, 96, 133, 240, 297, 448, 741, 840, 1225, 1512, 1653, 1984, 2553, 3192, 3397, 4128, 4641, 4888, 5757, 6360, 7345, 8784, 9525, 9880, 10665, 11040, 11869, 15168, 16137, 17680, 18165, 20976, 21505, 23280, 25125, 26368, 28329, 30360
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) is itself prime for a(1) = 3, a(2) = 5, ... a(n) is itself a perfect square for a(3) = 16 = 2^4, a(12) = 1225 = 5^2 * 7^2, .... a(n) is a semiprime for a(4) = 33 = 3 * 11, a(6) = 133 = 7 * 19, a(18) = 3397 = 43 * 79, ... - Jonathan Vos Post (jvospost3(AT)gmail.com), May 14 2005
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EXAMPLE
| a(5)=96 because 121 (fifth prime^2) - 25 (fifth square) = 96.
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MATHEMATICA
| Table[Prime[n]^2 - n^2, {n, 50}]
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CROSSREFS
| Cf. A014688, A076368, A075526, A001248, A000290.
Sequence in context: A080056 A019096 A077551 * A123785 A121646 A099101
Adjacent sequences: A106585 A106586 A106587 * A106589 A106590 A106591
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KEYWORD
| easy,nonn
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AUTHOR
| Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), May 10 2005
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), May 13 2005
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