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A069848
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Number of distinct primes obtained by inserting a 7 at all possible places in n. This includes prefixing as well as suffixing.
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9
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2, 0, 2, 1, 0, 1, 0, 0, 2, 1, 0, 1, 2, 0, 1, 1, 0, 0, 3, 0, 1, 1, 0, 0, 1, 0, 2, 0, 0, 1, 1, 0, 3, 1, 0, 1, 0, 0, 3, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 2, 0, 0, 1, 1, 0, 2, 1, 0, 1, 2, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 1, 1, 0, 1, 1, 0, 1, 2, 0, 1, 0, 0, 0, 1, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| See the example in A069842.
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MATHEMATICA
| Table[ Count[ PrimeQ[ Union[ FromDigits /@ Table[ Insert[ IntegerDigits[n], 7, j], {j, 1, Floor[ Log[10, n] + 2]}]]], True], {n, 1, 105}]
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CROSSREFS
| Cf. A069842, A069843, A069844, A069845, A069846, A069847, A069849, A069850 and A069851.
Sequence in context: A112604 A203399 A072627 * A194702 A118682 A198393
Adjacent sequences: A069845 A069846 A069847 * A069849 A069850 A069851
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 16 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 18 2002
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