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A102173
Iccanobirt semiprime indices (3 of 15): Indices of semiprime numbers in A102113.
1
5, 9, 11, 16, 22, 29, 67, 72, 87, 90, 94, 95, 119, 123, 146, 188, 323, 330
OFFSET
1,1
FORMULA
A102113(a(n)) = A102193(n).
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
EXTENSIONS
Offset changed to 1 and a(17)-a(18) from Jinyuan Wang, Aug 10 2021
STATUS
approved