A102173 Iccanobirt semiprime indices (3 of 15): Indices of semiprime numbers in A102113.

5, 9, 11, 16, 22, 29, 67, 72, 87, 90, 94, 95, 119, 123, 146, 188, 323, 330

Offset

1,1

Links

Table of n, a(n) for n=1..18.

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

Cf. A001358, A102113, A102171-A102185, A102193.

Sequence in context: A292089 A314600 A023484 * A171763 A342092 A089255

Adjacent sequences: A102170 A102171 A102172 * A102174 A102175 A102176

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