Indices i of pentagonal numbers P(i) such that (P(i)-1)/2 is also a pentagonal number.
A260937
Indices i of pentagonal numbers P(i) such that (P(i)-1)/2 is also a pentagonal number.
Terms
- a(0) =1a(1) =106a(2) =345a(3) =122130a(4) =397937a(5) =140937722a(6) =459218761a(7) =162642008866a(8) =529938052065
External references
- oeis: A260937