This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A114453 #18 Feb 04 2025 08:59:38
%S A114453 0,0,4,76,963,11185,124465,1349779,14371023,150982388,1570678136,
%T A114453 16218372618,166497674684,1701439985694,17323079621014,
%U A114453 175846040834673,1780617141307093,17993699600756449,181520864946969233
%N A114453 Number of 5-almost primes less than or equal to 10^n.
%e A114453 There are 4 five-almost primes up to 100: 32,48,72 and 80, so a(2) = 4.
%t A114453 FiveAlmostPrimePi[n_] := Sum[ PrimePi[n/(Prime@i*Prime@j*Prime@k*Prime@l)] - l + 1, {i, PrimePi[n^(1/5)]}, {j, i, PrimePi[(n/Prime@i)^(1/4)]}, {k, j, PrimePi[(n/(Prime@i*Prime@j))^(1/3)]}, {l, k, PrimePi[(n/(Prime@i*Prime@j*Prime@k))^(1/2)]}]; Table[ FiveAlmostPrimePi[10^n], {n, 0, 12}]
%o A114453 (Python)
%o A114453 from math import prod, isqrt
%o A114453 from sympy import primerange, integer_nthroot, primepi
%o A114453 def A114453(n):
%o A114453 def g(x,a,b,c,m): yield from (((d,) for d in enumerate(primerange(b,isqrt(x//c)+1),a)) if m==2 else (((a2,b2),)+d for a2,b2 in enumerate(primerange(b,integer_nthroot(x//c,m)[0]+1),a) for d in g(x,a2,b2,c*b2,m-1)))
%o A114453 return int(sum(primepi(10**n//prod(c[1] for c in a))-a[-1][0] for a in g(10**n,0,1,1,5))) # _Chai Wah Wu_, Sep 18 2024
%Y A114453 Cf. A006880, A066265, A109251, A014614, A116382.
%K A114453 nonn,more
%O A114453 0,3
%A A114453 _Robert G. Wilson v_, Feb 07 2006
%E A114453 a(13)-a(14) from _Robert G. Wilson v_, Jan 07 2007
%E A114453 a(15)-a(18) from _Henri Lifchitz_, Feb 03 2025