A165449 -id:A165449 - cp's OEIS frontend

A031297 a(n) is the least k such that the base-10 representation of n begins at s(k), where s=A007376.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 1, 16, 18, 20, 22, 24, 26, 28, 30, 15, 34, 2, 38, 40, 42, 44, 46, 48, 50, 17, 37, 56, 3, 60, 62, 64, 66, 68, 70, 19, 39, 59, 78, 4, 82, 84, 86, 88, 90, 21, 41, 61, 81, 100, 5, 104, 106, 108, 110, 23, 43, 63, 83

Offset: 1

Clark Kimberling

A229186 is the same sequence including the a(0) term.

			a(1) = a(12) = a(123) = 1 since they each start at index 1 in 0123.
a(21) = 15 since it appears first at index 15 in 012345678910111213.

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Cf. A007376, A229186 (same sequence but including the a(0) term).
Cf. A165449.
Cf. A030304 (binary variant).

with(StringTools): s:="": for n from 1 to 70 do s:=cat(s,convert(n,string)): od: seq(Search(convert(n, string), s), n=1..70); # Nathaniel Johnston, May 26 2011

nmax = 100;
s = Table[IntegerDigits[n], {n, 0, nmax}] // Flatten;
a[n_] := SequencePosition[s, IntegerDigits[n], 1][[1, 1]] - 1;
Array[a, nmax] (* Jean-François Alcover, Feb 21 2021 *)

from itertools import count, islice
def agen():
    k, chap = 0, "0"
    for n in count(1):
        target = str(n)
        while chap.find(target) == -1: k += 1; chap += str(k)
        yield chap.find(target)
print(list(islice(agen(), 70))) # Michael S. Branicky, Oct 06 2022

A229190 Beginning position of n in the decimal expansion of the Copeland-Erdos constant.

Original entry on oeis.org

48, 5, 1, 2, 21, 3, 31, 4, 41, 12, 47, 5, 62, 7, 22, 77, 32, 9, 95, 11, 589, 110, 113, 1, 128, 131, 137, 63, 149, 15, 158, 8, 14, 123, 24, 2, 188, 19, 42, 72, 206, 21, 215, 23, 227, 233, 236, 25, 248, 75, 257, 78

Offset: 0

Eric W. Weisstein, Sep 15 2013

Same as A165449 but including the a(0) term.

Eric W. Weisstein, Table of n, a(n) for n = 0..999
Eric Weisstein's World of Mathematics, Copeland-Erdos Constant Digits
Eric Weisstein's World of Mathematics, Constant Digit Scanning

Cf. A033308 (decimal expansion of the Copeland-Erdos constant).

Cf. A165449 (same sequence but omitting the a(0) term).

from sympy import primerange
from itertools import count, takewhile
def afind(plimit):
  s = "".join(str(p) for p in primerange(1, plimit+1))
  return [1+s.find(str(n)) for n in takewhile(lambda i: str(i) in s, count(0))]
print(afind(10**4)) # Michael S. Branicky, May 01 2021

cp's OEIS Frontend

A031297 a(n) is the least k such that the base-10 representation of n begins at s(k), where s=A007376.

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