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%I #21 Oct 18 2022 01:25:00
%S 0,1,3,7,9,16,22,29,35,39,50,57,68,84,100,112,127,151,167
%N The number of ratios t/(t-1), where t is a triangular number, which factor into primes less than or equal to prime(n).
%C As in the case of square numerators, triangular numerators of superparticular ratios m/(m-1) factorizable only up to a relatively small prime p are relatively common.
%C Equivalently, a(n) is the number of quadruples of consecutive prime(n)-smooth numbers. - _Lucas A. Brown_, Oct 04 2022
%H Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/stormer.py">stormer.py</a>.
%H E. F. Ecklund and R. B. Eggleton, <a href="http://www.jstor.org/stable/2317422">Prime factors of consecutive integers</a>, Amer. Math. Monthly, 79 (1972), 1082-1089.
%H D. H. Lehmer, <a href="http://projecteuclid.org/euclid.ijm/1256067456">On a problem of Størmer</a>, Ill. J. Math., 8 (1964), 57-79.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Stormer%27s_theorem">Størmer's theorem</a>
%e The ratios counted by a(3) are 3/2, 6/5, and 10/9.
%e The ratios counted by a(4) are 3/2, 6/5, 10/9, 15/14, 21/20, 28/27, and 36/35.
%Y Cf. A002071, A117582.
%K nonn,hard,more
%O 1,3
%A _Gene Ward Smith_, Apr 02 2006
%E a(14)-a(18) by _Lucas A. Brown_, Oct 04 2022
%E a(19) from _Lucas A. Brown_, Oct 16 2022