A068884 Largest n-digit triangular number with property that digits alternate in parity, or 0 if no such number exists.
6, 78, 903, 9870, 96141, 941878, 9850141, 98947278, 985036305, 9892547470, 98585094741, 989436909450, 9898947258903, 98969892923278, 989872901298945, 9898987276765450, 98985850965876105, 989898183850729896, 9898969072503098503
Offset: 1
Examples
a(4) = 9870 is a term as 9, 8, 7 and 0 have odd and even parity alternately.
Links
- Sean A. Irvine, Table of n, a(n) for n = 1..50
Extensions
a(6)-a(19) from Donovan Johnson, Mar 11 2011