This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Christopher J. Hanson's wiki page.
Christopher J. Hanson has authored 14 sequences. Here are the ten most recent ones:
{a(n) = my(A); if( n<1, 0, A = vector( n*50 + 148, k, k+1); for( i = 1, 4, A = select( k -> k%prime(i), A) ); polcoeff( (1 - x) * Ser( select( k -> k>11 && (k%11) == 0, A) / 11), n))}; /* Michael Somos, Mar 10 2014 */
{a(n) = my(A); if( n<1, 0, A = vector( n*28 + 48, k, k+1); for( i = 1, 3, A = select( k -> k%prime(i), A) ); polcoeff( (1 - x) * Ser( select( k -> k>7 && (k%7) == 0, A) / 7), n)) }; /* Michael Somos, Mar 10 2014 */
(C#)
// dp(4) = GeneratePrimeDifferencialPattern( 4 );
static void GeneratePrimeDifferencialPattern( int ordinal )
{
// Contract
if( ordinal < 1 )
throw new ArgumentOutOfRangeException( "ordinal" );
// Local data
int size = 1 << 18;
int[] numberLine = Enumerable.Range( 2, size ).ToArray();
int pointer = 0;
// Apply sieve: for each integer greater than 1
while( pointer < numberLine.Length )
{
// Locals
int x = numberLine[pointer];
int index = pointer;
List pattern = new List();
int skips = 0;
int count = 0;
bool counting = true;
// Find all products
for( int n = x + x; n < size; n += x )
{
// Fast forward through number-line
while( numberLine[++index] < n )
skips++;
// If the number was not already removed
if( numberLine[index] == n )
{
// Add skip count to pattern
pattern.Add( numberLine[index] );
// Mark as not prime
numberLine[index] = 0;
// Reset skips
if( counting )
{
count++;
if( skips <= 2 )
counting = false;
}
skips = 0;
}
// Otherwise we've skipped again
else skips++;
}
// Reduce number-line
numberLine = numberLine.Where( n => n > 0 ).ToArray();
// If we have a pattern we want
if( pattern.Any() && pointer == ordinal - 1 )
{
// Report pattern
int prime = numberLine[ordinal-1];
var d = pattern.Take( count ).ToArray();
List dp = new List();
for( int y = 1; y < count; y++ )
dp.Add( ( d[y] - d[y - 1] ) / prime );
System.Console.WriteLine( "Pattern P({0}) = {1} :: dp({0}) = {2}", pointer + 1, numberLine[pointer], String.Join( ", ", dp ) );
return;
}
// Move number-line pointer forward
pointer++;
}
}
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