A373079 Decimal digits of Pi selected by stepping forward d places at digit d or 10 places if d=0.
3, 1, 5, 3, 9, 2, 4, 3, 9, 7, 3, 1, 0, 4, 3, 8, 6, 8, 2, 3, 1, 1, 7, 1, 4, 6, 2, 0, 4, 5, 2, 3, 2, 3, 4, 2, 4, 1, 7, 1, 0, 1, 1, 0, 2, 4, 4, 3, 9, 9, 4, 2, 4, 4, 3, 6, 5, 0, 8, 6, 1, 0, 2, 3, 3, 7, 1, 4, 3, 4, 0, 8, 5, 0, 0, 6, 9, 3, 3, 4, 0, 1, 4, 1, 9, 4, 5, 3, 7, 5, 1, 8, 9, 1, 0, 4, 3, 9, 3, 8
Offset: 1
Examples
The sequence starts with the first digit of the decimal expansion of Pi, which is 3. The next term is the digit 3 places after this, namely, 1, and so on.
The digits selected from Pi begin
Pi = 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, ...
^ ^ ^ ^ ^
Programs
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Mathematica
a={3}; s=1; For[n=2, n<=100, n++, s+=Part[a,n-1]+10KroneckerDelta[Part[a,n-1]]; digits=First[RealDigits[Pi,10,s]]; AppendTo[a,Part[digits,s]]]; a (* Stefano Spezia, May 31 2024 *)
Formula
a(n) = the (1 + Sum_{i=1..n-1} a(i) + 10*delta(a(i),0))-th digit in the decimal expansion of Pi, where delta is the Kronecker symbol.
Extensions
a(25)-a(100) from Stefano Spezia, May 31 2024
Comments