add reference to sequence A002822

Author: ilanschnell

examples/dubner.py

@@ -39,6 +39,10 @@
 # consider multiples of 6.
 middles = twins[2::3] >> 1
 
+# The indices of 1 bits give sequence https://oeis.org/A002822
+lst = list(middles.search(1, 0, 46))
+assert lst == [1, 2, 3, 5, 7, 10, 12, 17, 18, 23, 25, 30, 32, 33, 38, 40, 45]
+
 # m is a middle number when middles[m//6].
 # The first middle numbers greater than 4 are:
 lst = [6 * i for i in middles.search(1, 0, 20)]