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A087630
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Number of n-digit primes == 1 (mod 10). E.g. there exist 5 two-digit prime numbers (11,31,41,61 and 71) with unit's place 1.
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0
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OFFSET
| 0,2
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EXAMPLE
| a(3)=35, since there are 35 three-digit numbers with unit place digit as 1.
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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==1) count=count+1; } c=0; } System.out.println("count = "+count);
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CROSSREFS
| Sequence in context: A196661 A104532 A180900 * A084135 A138233 A002294
Adjacent sequences: A087627 A087628 A087629 * A087631 A087632 A087633
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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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