20005

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 9.at n=30A031422
• Squarefree n such that the elliptic curve n*y^2 = x^3 - x arising in the "congruent number" problem has rank 3.at n=33A062693
• List the positions of all digits '1' in the sequence. This is the lexicographically earliest increasing sequence with this property.at n=43A098645
• Primitive sliding numbers (excludes multiples of 10): totals, including repetitions, of sums r + s, r >= s, such that 1/r + 1/s = (r + s)/10^k for some k >= 0.at n=34A103184
• Members of 3-cycles of permutation A111273.at n=17A113701
• Numbers k such that k and k^2 use only the digits 0, 2, 3, 4 and 5.at n=35A136882
• Numbers k such that k and k^2 use only the digits 0, 2, 4 and 5.at n=24A136897
• Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 6.at n=44A136898
• Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 7.at n=36A136899
• Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 8.at n=36A136900
• Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 9.at n=38A136901
• Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 11000-01110-00011 pattern in any orientation.at n=12A147188
• Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 11000-01110-00011 pattern in any orientation.at n=26A147190
• Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 11000-01110-00011 pattern in any orientation.at n=27A147190
• Numbers k such that k^3 divides 14^(k^2) + 1.at n=19A177814
• Beach-Williams Pell numbers of type pq (p,q primes).at n=16A212078
• Let x(0)x(1)x(2)... x(q) denote the decimal expansion of n. Sequence lists the numbers n such that the suffix of decimal expansion x(1)x(2)... x(q) is the x(0)-th divisor of n.at n=31A234314
• Array T(n,k) = least integer congruent to prime(i) mod prime(i+1) for all k <= i <= k+n; n, k >= 1; read by upward diagonals.at n=24A268491
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 798", based on the 5-celled von Neumann neighborhood.at n=32A273571
• First differences of A260443.at n=20A277197