cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

Original entry on oeis.org

5, 9, 11, 16, 22, 29, 67, 72, 87, 90, 94, 95, 119, 123, 146, 188, 323, 330
Offset: 1

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Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

Crossrefs

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

Programs

  • 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 *)

Formula

A102113(a(n)) = A102193(n).

Extensions

Offset changed to 1 and a(17)-a(18) from Jinyuan Wang, Aug 10 2021
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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