OFFSET
1,1
MATHEMATICA
nxt[{a1_, a2_, a3_}]:={a2, a3, a3+FromDigits[Reverse[IntegerDigits[a1]]]+ FromDigits[Reverse[IntegerDigits[a2]]]}; Flatten[Position[Transpose[ NestList[nxt, {0, 0, 1}, 200]][[1]], _?(PrimeOmega[#]==2&)]]-1 (* Harvey P. Dale, Oct 17 2012 *)
CROSSREFS
KEYWORD
nonn,more,less,base
AUTHOR
Jonathan Vos Post and Ray Chandler, Dec 31 2004
EXTENSIONS
Offset changed to 1 and a(17)-a(18) from Jinyuan Wang, Aug 10 2021
STATUS
approved