A249342 - OEIS

%I #11 Oct 26 2014 20:51:46

%S 1,2,6,13,20,39,45,70,80,97,121,145,193,240,257,296,322,379,400,432,

%T 481,490,532,566,632,715,760,766,807,835,878,1067,1104,1209,1215,1369,

%U 1414,1468,1514,1540,1605,1683,1706,1853,1871,1905,1935,2116,2276,2293,2304,2343

%N Position of the first occurrence of n-th noncomposite number, A008578(n), in A249337; positions of records in A249072.

%F For all n >= 1:

%F A249337(a(n)) = A008578(n).

%F A249072(a(n)) = n-1.

%F For all n >= 2:

%F a(n) = A249341(n) - 1.

%o (Scheme, with _Antti Karttunen_'s IntSeq-library, two alternative definitions)

%o (define A249342 (MATCHING-POS 1 1 (lambda (n) (or (= 1 n) (and (= 1 (A249337 (+ 1 n))) (prime? (A249337 n)))))))

%o (define A249342 (RECORD-POS 1 1 A249072))

%Y After the initial term, one less than A249341.

%Y Cf. A008578, A249337, A249340, A249072.

%K nonn

%O 1,2

%A _Antti Karttunen_, Oct 26 2014