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Search: id:A087633
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| A087633 |
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Number of n-digit primes == 9 (mod 10). E.g. there exist 5 two-digit prime numbers(19,29,59,79 and 89) with unit's place 9. |
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+0
1
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| 0, 5, 33, 265, 2087, 17203, 146439, 1274154, 11271147, 101049993
(list; graph; listen)
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OFFSET
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0,2
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EXAMPLE
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E.g. a(3)=33, since there are 33 three-digit numbers with unit place digit as 9.
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PROGRAM
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(JAVA) The terms of the sequences are generated by changing the range for j for the various number of digits. E.g. it ranges from 100 to 999 for three-digit numbers. float r, x; int c=0, count=0; for (float j=100f; j<1000f; j++) { for (float i=2f; i<j; i++) { r=j%i; if (r==0) c=1; } if (c == 0) { x=j%10; if (x==9) count=count+1; } c=0; } System.out.println("count = "+count);
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CROSSREFS
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Sequence in context: A056159 A061253 A111530 this_sequence A135075 A049377 A129890
Adjacent sequences: A087630 A087631 A087632 this_sequence A087634 A087635 A087636
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KEYWORD
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nonn
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AUTHOR
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Meenakshi Srikanth and Amarnath Murthy (menakan_s(AT)yahoo.com), Sep 15 2003
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EXTENSIONS
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Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 04 2003
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