login
The middle point of row n in binary beanstalk related sequences A179016, A218602, A218616, A233270, A233271.
6

%I #16 May 22 2014 03:31:33

%S 1,2,3,6,10,17,30,53,95,171,310,564,1036,1918,3574,6691,12566,23653,

%T 44610,84309,159698,303253,577352,1102121,2109448,4047967,7787277,

%U 15015347,29011671,56150867,108825599,211127246,409886210,796134319,1546848744,3006198333,5843799964

%N The middle point of row n in binary beanstalk related sequences A179016, A218602, A218616, A233270, A233271.

%C a(n) points to the center of each palindromic row/subrange of A233270, and to the lower position nearest to the center, if the length of range is even.

%C For all n, A218602(a(n)) = a(n) + (1-A000035(A213709(n-1))).

%F a(n) = floor((A213710(n-1) + A218600(n)) / 2).

%F a(n) = A218600(n-1) + ceiling((A213709(n-1)/2)).

%o (MIT/GNU Scheme, two alternative versions)

%o (define (A233268 n) (floor->exact (/ (+ (A213710 (- n 1)) (A218600 n)) 2)))

%o (define (A233268 n) (+ (A218600 (- n 1)) (ceiling->exact (/ (A213709 (- n 1)) 2))))

%Y Cf. A213709, A213710, A218600, A234018, A234019, A234020.

%Y Cf. also A179016, A218602, A218616, A233270, A233271.

%K nonn

%O 1,2

%A _Antti Karttunen_, Dec 29 2013