A052213 Numbers n with prime signature(n) = prime signature(n+1)

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Jul 21st, 2010
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1. #include <iostream>
2. #include <vector>
3. #include <algorithm>
4.
5. using namespace std;
6.
7. template<class T>
8. string str( const vector<T>& v )
9. {
10. stringstream ss;
11. for ( int i = 0; i < (int)v.size(); i++ )
12. ss << (i?",":"") << v[i];
13. return "{" + ss.str() + "}";
14. }
15.
16. void getPrimeFactorsSig( __int64 x, vector<int>& v )
17. {
18. v.clear();
19. for ( __int64 i = 2; i*i <= x; i++ )
20. {
21. int power = 0;
22. while ( x % i == 0 )
23. x /= i, ++power;
24. if ( power )
25. v.push_back( power );
26. }
27. if ( x != 1 )
28. v.push_back( 1 );
29. sort( v.begin(), v.end() );
30. }
31. vector<int> getPrimeFactorsSig( __int64 x )
32. {
33. vector<int> v;
35. return v;
36. }
37.
38. void main()
39. {
40. __int64 K = 1000000000LL;
41. for ( __int64 i = K + 0; i < K + 4000; i++ )
42. {
43. vector<int> a = getPrimeFactorsSig( i );
44. vector<int> b = getPrimeFactorsSig( i+1 );
45. if ( a == b )
46. {
47. cout << i << " " << str(a) << endl;
48. }
49. }
50. }