22154

Appears in sequences

• a(n) is the concatenation of n and 7n.at n=21A009441
• Numbers n such that phi(n) + phi(n+1) = sigma(n)/2.at n=15A076647
• Absolute row sums of triangle A104967.at n=25A104968
• A symmetrical triangle:q=2;c(n,q)=Product[1 - q^i, {i, 1, n}];t(n,m,q)=A060187(n,m)-c(n,q)/(c(m,q)*c(n-m,q))+1.at n=24A176467
• Numbers k such that 10^k - sigma(k^2) is prime.at n=7A193881
• Number of nondecreasing -n..n vectors of length 3 whose dot product with some other -n..n vector equals 3.at n=25A226342
• Partitions with parts repeated at most twice and repetition only allowed if first part has an odd index (first index = 1).at n=54A227134
• Number of Motzkin paths of length n with all ascents ending at even heights.at n=15A299270
• Numbers k such that k and k+1 are the product of exactly four distinct primes.at n=17A318896
• Numbers k such that k and k+1 each have at least 4 distinct prime factors.at n=35A321504
• Numbers k such that k^2, (k+1)^2 and (k+2)^2 are all abundant numbers.at n=8A383391