20253

Appears in sequences

• a(1) = 7; a(n+1) = a(n)-th composite.at n=37A025011
• s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = [ n/2 ], s = (composite numbers).at n=43A025102
• Base-9 palindromes that start with 3.at n=27A043030
• Coefficients of replicable function number 12b.at n=13A058490
• a(n) is the smallest number k such that A073813(k) = prime(n).at n=35A073814
• Least m such that P - m is prime, where P is the n-th perfect number.at n=21A078097
• a(n) is such that the a(n)-th composite number is (n-th prime)^2.at n=35A120389
• Trajectory of 13 under map n -> A132948(n).at n=28A132946
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 1, 0), (-1, 1, 1), (1, 0, 0)}.at n=10A148549
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (0, 1, 0), (1, 1, 0), (1, 1, 1)}.at n=7A151173
• Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, -1), (0, 1), (1, -1)}.at n=10A151263
• Number of (w,x,y) with all terms in {0,...,n} and w<x+y and x<y.at n=36A212980
• Prime time numbers on 6-digit clocks: numbers of the form HMMSS where H, MM, SS are primes, H < 24, MM and SS < 60.at n=15A295014
• Number of partitions of n with up to four distinct kinds of 1.at n=33A320691
• Number of partitions of n with up to nine distinct kinds of 1.at n=19A320696
• Number of strict compositions of n with all adjacent parts (x, y) satisfying x <= 2y and y <= 2x.at n=48A342342
• a(n) = Sum_{k=1..n} k^floor((n-k)/k).at n=27A344551
• Row sums of the accumulated Stirling2 triangle A359107.at n=8A359109