|
Search: id:A087632
|
|
|
| A087632 |
|
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. |
|
+0
1
|
|
| 1, 5, 40, 262, 2103, 17210, 146590, 1274284, 11271819, 101051725
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
EXAMPLE
|
E.g. a(3)=40, since there are 40 three-digit numbers with unit place digit as 7.
|
|
PROGRAM
|
(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);
|
|
CROSSREFS
|
Sequence in context: A043019 A054604 A001656 this_sequence A124306 A124545 A125729
Adjacent sequences: A087629 A087630 A087631 this_sequence A087633 A087634 A087635
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Meenakshi Srikanth adn Amarnath Murthy (menakan_s(AT)yahoo.com), Sep 15 2003
|
|
EXTENSIONS
|
More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 04 2003
|
|
|
Search completed in 0.002 seconds
|
