21372

Appears in sequences

• Visible factor numbers (VFNs): composite numbers k with the property that every prime factor of k can be found in the decimal expansion of k and every digit of k can be covered by a prime factor.at n=3A083359
• Subsequence of sequence A083359 in which every prime factor can be found in the number at least as often as it is factor of the number.at n=0A083361
• Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)+1 are twin primes with p(h) = h-th prime.at n=41A129310
• Composite numbers, not ending with 0, sharing a 3-digit sequence with some of its prime factors.at n=21A131523
• Smallest number containing exactly n prime factors in its decimal representation.at n=4A131931
• 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, 0), (-1, 0, 1), (1, 0, -1), (1, 0, 0), (1, 1, -1)}.at n=10A148350
• Fourth entry in row n of triangle in A169945.at n=19A169948
• Row square-sums of triangle A096815.at n=11A212265
• Numbers n such that the sum of the numbers in the Collatz (3x+1) iteration of n is a perfect square.at n=43A225866
• Number of (n+1)X(1+1) 0..2 arrays colored with the maximum plus the upper median plus the lower median of every 2X2 subblock.at n=3A236658
• Number of (n+1)X(4+1) 0..2 arrays colored with the maximum plus the upper median plus the lower median of every 2X2 subblock.at n=0A236661
• T(n,k)=Number of (n+1)X(k+1) 0..2 arrays colored with the maximum plus the upper median plus the lower median of every 2X2 subblock.at n=6A236663
• T(n,k)=Number of (n+1)X(k+1) 0..2 arrays colored with the maximum plus the upper median plus the lower median of every 2X2 subblock.at n=9A236663
• Number of partitions of n with difference 9 between the number of odd parts and the number of even parts, both counted without multiplicity.at n=38A242700
• Number of (n+2) X (1+2) 0..1 arrays with every 2 X 2 and 3 X 3 subblock diagonal maximum minus antidiagonal minimum nondecreasing horizontally and vertically.at n=30A253503
• Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with five.at n=7A292171
• a(1) = 2; for n > 1, a(n) is the least positive number not yet in the sequence such that Sum_{k=1..n} a(k) divides Sum_{k=1..n} a(k)^2.at n=39A318358
• a(n) is the smallest number containing all its n prime factors in its decimal representation.at n=3A318965
• a(n) is the smallest number with n distinct prime factors whose decimal representation contains all its prime factors, taking multiplicity into account.at n=3A319022
• Zerofree numbers k such that the product (m+n)*p, where m,n are the first and the last digits of k, and p is the number which is the part of k between m and n, is a divisor of k.at n=26A320292