A277827 - OEIS

%I #33 Aug 07 2023 13:29:15

%S 3,8,9,4,9,1,6,4,5,2,1,1,1,5,5,4,2,4,8,6,3,4,3,6,6,3,0,6,5,8,8,0,1,3,

%T 8,6,1,3,1,1,1,4,9,8,2,1,3,3,4,6,2,7,6,0,0,7,7,7,4,2,2,9,1,4,7,7,9,1,

%U 9,9,9,9,9,9,4,5,2,3,4,1,8,0,0,8,3,7,6,5,1,8,7,7,2,6,0,6,1,1,8,3

%N Digits that appear twice consecutively in the decimal expansion of Pi, in order of appearance.

%C A digit d of Pi is in this sequence iff A000796(i) = A000796(i+1), where i is the index of d in A000796. - _Felix Fröhlich_, Nov 01 2016

%F a(n) = A000796(A049514(n)).

%e Pi=3.14159265358979323846264(33)83279502(88)41971693(99)3751058209749(44)592307816406286208(99)8628034825342(11)70679...

%e Therefore, this sequence starts 3, 8, 9, 4, 9, 1.

%o (PARI) pidigit(n) = floor(Pi*10^n) - 10*floor(Pi*10^(n-1))

%o terms(n) = my(k=1, i=0); while(1, if(pidigit(k)==pidigit(k+1), print1(pidigit(k), ", "); i++); if(i==n, break); k++)

%o /* Print initial 100 terms as follows */

%o terms(100) \\ _Felix Fröhlich_, Nov 01 2016

%Y Cf. A000796, A049514.

%K nonn,base

%O 1,1

%A _Bobby Jacobs_, Nov 01 2016