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A087632
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Number of n-digit primes == 7 (mod 10). E.g. there exist 5 two-digit prime numbers(17,37,47,67 and 97) with unit's place 7.
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0
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OFFSET
| 0,2
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EXAMPLE
| E.g. a(3)=40, since there are 40 three-digit numbers with unit place digit as 7.
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PROG
| (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==7) count=count+1; } c=0; } System.out.println("count = "+count);
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CROSSREFS
| Sequence in context: A054604 A157794 A001656 * A124306 A124545 A125729
Adjacent sequences: A087629 A087630 A087631 * A087633 A087634 A087635
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KEYWORD
| nonn,base
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AUTHOR
| Meenakshi Srikanth and Amarnath Murthy (menakan_s(AT)yahoo.com), Sep 15 2003
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EXTENSIONS
| More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 04 2003
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