44447

Appears in sequences

• Start with 1, apply 1->12, 21->21, 22->21, 2->2 (for final 2); a(n) = length of n-th term.at n=33A013950
• Numbers having four 4's in base 10.at n=22A043508
• Number of planar n X n X n binary triangular grids symmetric under 120 degree rotation with no more than 2 ones in any 5 X 5 X 5 subtriangle.at n=16A153917
• a(n) = (4*10^n + 23)/9.at n=4A173772
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 219", based on the 5-celled von Neumann neighborhood.at n=39A270932
• Numbers with digits 4 and 7 only.at n=31A284971
• Lexicographically first sequence of distinct terms such that the sum of any two terms is not a term of the sequence, and the sum of any two digits is not a digit of the sequence.at n=33A302938
• Indices of Ulam prime triples, where u(k), u(k+1) and u(k+2) are all primes, and u(k) = A002858(k) are the Ulam numbers.at n=20A307330
• Nonsquarefree numbers k such that A003415(k) divides A276086(k), where A003415 is the arithmetic derivative, and A276086 is the primorial base exp-function.at n=49A371085