22879

Appears in sequences

• Fibonacci sequence beginning 3, 7.at n=18A022120
• a(2n) = concatenation of 4n+1 and 4n+2, a(2n+1) = concatenation of the two most nearly equal numbers whose product is a(2n).at n=29A068517
• a(n) = (27*n^2 + 9*n + 2)/2.at n=41A093485
• a(n) = 4*a(n-1) -3*a(n-2) -2*a(n-3) +a(n-4), n>8.at n=13A108140
• a(n) = a(n-1) + 2*n^2 with a(1) = 1.at n=31A112524
• Semiprime centered triangular numbers.at n=45A184481
• a(n) = a(n-1) + a(n-2) + a(n-3), with a(0) = 1, a(1) = a(2) = 7.at n=15A214829
• Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + ... + d_(2)*10 + d_(1). Sequence lists the numbers n such that n' = Sum_{i=1..k-1}{Sum_{j=1..i}{d_(j)*10^(j-1)}}', where n' is the arithmetic derivative of n (see example below).at n=40A244078
• a(n) = k*Fibonacci(2*n+1) + (k+1)*Fibonacci(2*n), where k=3.at n=9A271357
• Partial sums of A299259.at n=29A299265
• A self-"read and extend" sequence built following the rules visible in the Comments section (a kind of Collatz-by-digits sequence).at n=39A316764
• Sum of the distinct block sizes over all partitions of [n].at n=8A350175
• Squarefree semiprimes that are centered triangular numbers.at n=42A380913