added oeis cheat sheet (chubin/cheat.sheets#187)

sheets/oeis

@@ -0,0 +1,13 @@
+# oeis
+#
+# The On-Line Encyclopedia of Integer Sequences (OEIS),
+# also cited simply as Sloane's, is an online database of integer sequences.
+
+# Find all possible OEIS sequences for some sequence (1,1,1,1...)
+curl cheat.sh/oeis/1+1+1+1
+
+# Implementation of the A2 OEIS sequence in Python
+curl cheat.sh/oeis/A2/python
+
+# List all available implementations of the A2 OEIS sequence
+curl cheat.sh/oeis/A2/:list