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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A081024 Complement of A081023: actual locations of "t" in this wholly inaccurate variation of the Aronson sentence: "T is the second, third, fifth, sixth, seventh . . . letter of this sentence, not counting commas or spaces".

Original entry on oeis.org

1, 4, 13, 21, 26, 33, 39, 44, 46, 49, 57, 59, 64, 70, 74, 79, 83, 88, 92, 99, 103, 109, 113, 119, 123, 125, 129, 132, 134, 138, 146, 150, 152, 157, 161, 167, 169, 173, 178, 180, 184, 191, 193, 197, 203, 205, 209, 214, 216, 220, 223, 225, 229, 235, 236, 240, 248
Offset: 1

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Author

Matthew Vandermast, Mar 02 2003

Keywords

Crossrefs

Cf. A005224 (Aronson sequence).

A005224 T is the first, fourth, eleventh, ... letter in this sentence, not counting spaces or commas (Aronson's sequence).

Original entry on oeis.org

1, 4, 11, 16, 24, 29, 33, 35, 39, 45, 47, 51, 56, 58, 62, 64, 69, 73, 78, 80, 84, 89, 94, 99, 104, 111, 116, 122, 126, 131, 136, 142, 147, 158, 164, 169, 174, 181, 183, 193, 199, 205, 208, 214, 220, 226, 231, 237, 243, 249, 254, 270, 288, 303, 307, 319, 323, 341
Offset: 1

Views

Author

Keywords

Comments

a(10^9) = 11281384554. - Hans Havermann, Apr 21 2017
First differences start: 3, 7, 5, 8, 5, 4, 2, 4, 6, 2, 4, 5, 2, 4, 2, 5, 4, 5, 2, 4, 5, 5, 5, 5, 7, 5, 6, 4, 5, 5, 6, 5, 11, 6, 5, 5, 7, 2, 10, 6, ... - Daniel Forgues, Sep 11 2019
Named after the British clinical pharmacologist Jeffrey Kenneth Aronson (b. 1947). - Amiram Eldar, Jun 23 2021

Examples

			The sentence begins
1234567890 1234567890 1234567890 1234567890 1234567890
Tisthefirs tfourthele venthsixte enthtwenty fourthtwen
tyninththi rtythirdth irtyfiftht hirtyninth fortyfifth
fortyseven thfiftyfir stfiftysix thfiftyeig hthsixtyse
condsixtyf ourthsixty ninthseven tythirdsev entyeighth
eightiethe ightyfourt heightynin thninetyfo urthninety
ninthonehu ndredfourt honehundre deleventho nehundreds
ixteenthon ehundredtw entysecond onehundred twentysixt
honehundre dthirtyfir stonehundr edthirtysi xthonehund
redfortyse cond...
		

References

  • J. K. Aronson, quoted by D. R. Hofstadter in Metamagical Themas, Basic Books, NY, 1985, p. 44.
  • James Gleick, Faster, Vintage Books, NY, 2000 (see pp. 259-261).
  • N. J. A. Sloane, Seven Staggering Sequences, in Homage to a Pied Puzzler, E. Pegg Jr., A. H. Schoen and T. Rodgers (editors), A. K. Peters, Wellesley, MA, 2009, pp. 93-110.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    seed="tisthe"; s[1]=1;s[2]=4;
    name[n_]:=StringReplace[IntegerName[n,{"English","Ordinal"}],{"-"->""," "->""}];
    s[n_]:=seed=StringJoin[seed<>name[StringPosition[seed,"t"][[n-2,1]]]];
    l=s/@Range[58]; Table[StringPosition[Last[l],"t"][[i,1]],{i,1,Length[l]}] (* Ivan N. Ianakiev, Mar 25 2020 *)
  • Python
    from num2words import num2words
    from itertools import islice
    def n2w(n):
        os = num2words(n, ordinal=True).replace(" and", "")
        return os.replace(" ", "").replace("-", "").replace(chr(44), "")
    def agen(): # generator of terms
        s, idx = "tisthe", 0
        while True:
            idx_rel = 1 + s.index("t")
            idx += idx_rel
            yield idx
            s = s[idx_rel:] + n2w(idx)
    print(list(islice(agen(), 58))) # Michael S. Branicky, Mar 18 2022

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Oct 31 2000
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