20000000

Appears in sequences

• Powers of 2 written in base 4.at n=15A004643
• Powers of 2 written in base 8.at n=22A004647
• Powers of 2 written in base 16.at n=29A004655
• Number of spanning trees in the graph K_{n}/e, which results from contracting an edge e in the complete graph K_{n} on n vertices (for n>=2).at n=8A007334
• Numbers k such that k^2 contains exactly 2 distinct digits.at n=40A016069
• a(n)/10000000 gives sqrt(n) to 7 places.at n=3A027664
• Numbers k such that k^2 + k + 4 is a palindrome.at n=20A027716
• Numbers k such that k^3 has at most two different digits.at n=20A030292
• a(n) = floor(10^8/n).at n=4A033424
• a(n) = ceiling(sqrt(4*10^n)).at n=14A035071
• Triangle whose (i,j)-th entry is binomial(i,j)*10^(i-j)*10^j.at n=24A038312
• Ambitious numbers: numbers n with the property that if a number ends in n then it is divisible by n.at n=34A039690
• a(n) is the index of the smallest triangular number containing exactly n 0's.at n=12A048355
• Expansion of g.f. (1+2*x+5*x^2)/(1-10*x^3).at n=22A051109
• Sums of two powers of 10.at n=35A052216
• Triangle read by rows: T(j,k) is the number of acyclic functions from {1,...,j} to {1,...,k}. For n >= 1, a(n) = (k-j)*k^(j-1), where k is such that C(k,2) < n <= C(k+1,2) and j = (n-1) mod C(k,2). Alternatively, table T(k,j) read by antidiagonals with k >= 1, 0 <= j <= k: T(k,j) = number of acyclic-function digraphs on k vertices with j vertices of outdegree 1 and (k-j) vertices of outdegree 0; T(k,j) = (k-j)*k^(j-1).at n=53A058127
• Multiples of 2 whose digit sum is 2.at n=28A069537
• n, n^2 and n^3 all use only even digits.at n=23A085586
• Duplicate of A007334.at n=8A089104
• Triangle, read by rows, of coefficients for the second iteration of the hyperbinomial transform.at n=36A089460