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A307463
a(n) is the digit after the appearance of n in the decimal numbers of Pi after all the previous natural numbers of n have already appeared except for 0, and without overlap.
0
4, 6, 5, 6, 0, 9, 5, 2, 7, 2, 0, 8, 3, 1, 5, 0, 3, 5, 4, 0, 4, 4, 5, 4, 2, 1, 8, 3, 5, 0, 5, 1, 4, 5, 6, 0, 1, 9, 0, 7, 0, 7, 1, 6, 1, 7, 9, 9, 3, 6, 2, 0, 9, 8, 2, 4, 0, 6, 8, 8, 4, 2, 4, 7, 4, 6, 2, 7, 5, 1, 6, 0, 4, 1, 4, 3, 6, 3, 6, 7, 6, 9, 1, 5, 3, 0, 4, 1
OFFSET
1,1
COMMENTS
All terms appear in the decimal expansion of Pi.
EXAMPLE
See the first decimal digits of Pi for the examples:
3.(1)4159(2)65(3)589793238(4)62643383279(5)0288...
In parentheses the first appearing of natural numbers after all smaller natural numbers have already appeared.
- FIRST ELEMENT a(1):
For n=1, the first '1' appears in the first decimal place of Pi, and the next decimal digit is '4', so a(1)=4.
- DIGIT POSITION:
For n=4, although the first 4 appears in the 2 decimal place, not all the previous natural numbers of 4 have appeared, so, after 1, 2, and 3 have appeared (in this order), then, a(4) will be the next digit after the next 4. So a(4)=6.
- N WITH MORE THAN 1 DIGIT:
In the decimal digits of Pi: ...50284(10)270193852(11)05...
For n with more than 1 digit, a(n) is, after all the previous natural numbers have appeared, the next digit after all the digits of n have appeared consecutively. Example: a(10)=2, a(11)=0.
- NO OVERLAP:
In the decimal digits of Pi: ...52230825(33)44685035...730359825(34)904...
Example: for n=33, a(33)=4, but, as there is no overlap, the '3' cannot be used again with the '4' for n=34, so a(34) is defined by the next 34: a(34)=9.
PROG
(PARI) lista(nn, t=10^5) = {default(realprecision, t); my(d, k=1, v=digits(floor(Pi*10^t))); for(n=1, nn, d=digits(n); while(v[k..k+#d-1]!=d, k++); k+=#d; print1(v[k], ", ")); } \\ Jinyuan Wang, Feb 18 2021
CROSSREFS
Sequence in context: A271365 A088559 A092526 * A243396 A140243 A366872
KEYWORD
nonn,base
AUTHOR
Marc Bofill Janer, Apr 09 2019
EXTENSIONS
More terms from Jinyuan Wang, Feb 18 2021
STATUS
approved