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.

A030303 Position of n-th 1 in A030302.

Original entry on oeis.org

1, 2, 4, 5, 6, 9, 11, 12, 13, 15, 16, 17, 18, 22, 25, 26, 28, 30, 32, 33, 34, 35, 38, 39, 41, 42, 43, 44, 46, 47, 48, 49, 50, 55, 59, 60, 63, 65, 68, 69, 70, 72, 75, 77, 79, 80, 82, 83, 85, 87, 88, 89, 90, 91, 95, 96, 99, 100, 101, 103, 105, 106, 108, 109, 110, 111, 112, 115, 116, 117, 119, 120
Offset: 1

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Comments

Partial sums of A066099; also positions of 1's in the Champernowne word A030190 which therefore is the characteristic function of this sequence seen as a set. The graph of this sequence has a self-similar shape with increasingly important "cusps" at indices given by A005183, which also indexes records in A066099. - M. F. Hasler, Oct 12 2020

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndices)
    a030303 n = a030303_list !! n
    a030303_list = elemIndices 1 a030190_list
    -- Reinhard Zumkeller, Dec 11 2011
    
  • Mathematica
    Flatten[Position[Flatten[IntegerDigits[Range[30],2]],1]] (* Harvey P. Dale, Jan 04 2015 *)
  • PARI
    select(t->t,concat([binary(n)|n<-[1..30]]),1) \\ M. F. Hasler, Oct 10 2020
    
  • Python
    from itertools import count, islice
    def A030303_gen(): # generator of terms
        return (i + 1 for i, s in enumerate(d for n in count(1) for d in bin(n)[2:]) if s == '1')
    A030303_list = list(islice(A030303_gen(),30)) # Chai Wah Wu, Feb 18 2022

Formula

A030190(a(n)) = 1. - Reinhard Zumkeller, Dec 11 2011
a(n) = Sum_{k=1..n} A066099(k). - M. F. Hasler, Oct 12 2020

Extensions

More terms from M. F. Hasler, Oct 12 2020