A102195 Iccanobirt semiprimes (5 of 15): Semiprime numbers in A102115.

4, 779, 1138, 57415, 77633, 55486847, 1073911003, 3317721397, 1060433508262511, 71024113009688593314067, 11974445409544006175987023, 1076202964567631961558639609002933, 33696092853645518103687453241761538, 4617443279524324394317910914689160360213

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..19

Formula

a(n) = A102115(A102175(n)).

Mathematica

nxt[{a_, b_, c_}]:={b, c, Total[FromDigits/@Reverse/@IntegerDigits[{a, c}]]+b}; Select[NestList[nxt, {0, 0, 1}, 120][[;; , 1]], PrimeOmega[#]==2&] (* Harvey P. Dale, Mar 02 2025 *)

Crossrefs

Cf. A001358, A102115, A102191-A102205.

Sequence in context: A306254 A068112 A007725 * A114766 A239623 A202685

Adjacent sequences: A102192 A102193 A102194 * A102196 A102197 A102198

Keyword

nonn,less,base

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Extensions

Offset changed to 1 and a(14) from Jinyuan Wang, Aug 12 2021

Status

approved