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Search: id:A069842
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| A069842 |
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Number of distinct primes obtained by inserting a 1 at all possible places in n. This includes prefixing and suffixing. |
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+0
10
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| 1, 0, 2, 1, 0, 1, 2, 0, 1, 1, 0, 0, 2, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 2, 1, 0, 0, 2, 0, 2, 0, 0, 0, 2, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 3, 0, 1, 1, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 3, 1, 0, 1, 2, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 0, 2, 1, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 1, 1, 0, 0, 2, 0, 3, 0, 0, 1, 3, 0, 1
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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a(13) = 2 because 13 -> 113, 113, 131 -> 113 and 131 which are both prime.
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MATHEMATICA
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Table[ Count[ PrimeQ[ Union[ FromDigits /@ Table[ Insert[ IntegerDigits[n], 1, j], {j, 1, Floor[ Log[10, n] + 2]}]]], True], {n, 1, 105}]
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CROSSREFS
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Cf. A069843, A069844, A069845, A069846, A069847, A069848, A069849, A069850, A069851.
Sequence in context: A085860 A046810 A039999 this_sequence A083056 A061896 A069850
Adjacent sequences: A069839 A069840 A069841 this_sequence A069843 A069844 A069845
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 16 2002
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 17 2002
Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 18 2002
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