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Search: id:A111033
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| A111033 |
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Sum of squares of digits of pi. |
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+0
3
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| 9, 10, 26, 27, 52, 133, 137, 173, 198, 207, 232, 296, 377, 426, 507, 516, 520, 529, 593, 609, 645, 649, 685, 701, 710, 719, 783, 792, 796, 845
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) is prime for n = 7, 8, 19, 24, 26, ... a(n) is semiprime for n = 1, 2, 3, 6, 13, 18, 22, 23, ... a(n) is a perfect power for n = 1, 4, 18, ...
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FORMULA
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a(n) = sum(i=1 to n) A000796(i)^2.
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EXAMPLE
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a(1) = 3^2 = 9,
a(2) = 3^2 + 1^2 = 10,
a(3) = 3^2 + 1^2 + 4^2 = 26,
a(4) = 3^2 + 1^2 + 4^2 + 1^2 = 27,
a(5) = 3^2 + 1^2 + 4^2 + 1^2 + 5^2 = 52,
a(6) = 3^2 + 1^2 + 4^2 + 1^2 + 5^2 + 9^2 = 133,
a(7) = 3^2 + 1^2 + 4^2 + 1^2 + 5^2 + 9^2 + 2^2 = 137, which is prime.
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CROSSREFS
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Cf. A000796.
Sequence in context: A109463 A061410 A025043 this_sequence A123048 A041170 A041168
Adjacent sequences: A111030 A111031 A111032 this_sequence A111034 A111035 A111036
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KEYWORD
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base,easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Oct 05 2005
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