A102205 Iccanobirt semiprimes (15 of 15): Semiprime numbers in A102125.

4, 5071, 6313, 31591, 9853, 11733, 31865, 736481, 9834802, 5123383, 906334841, 312395329, 73044385753, 39216355244851, 353123779923181, 944016528715333, 901870160743125919, 3394064622591216338731, 798539095539570459224764519, 5844680137439021618014007903

Offset: 1

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

• nonn
• less
• base

Crossrefs

Cf. A001358, A102125, A102185, A102191-A102204.

Programs

Mathematica

nxt[{a_,b_,c_}]:=With[{ir=IntegerReverse},{b,c,ir[ir[a]+ir[b]+ir[c]]}]; Select[NestList[nxt,{0,0,1},200][[;;,1]],PrimeOmega[#]==2&] (* Harvey P. Dale, Jul 22 2025 *)

Formula

a(n) = A102125(A102185(n)).

Extensions

Offset changed to 1 and a(20) from Jinyuan Wang, Aug 14 2021