100128

Appears in sequences

• Smallest n-digit triangular number.at n=5A068093
• Smallest k whose 'Reverse and Subtract' trajectory has a preperiodic part of length n.at n=23A072138
• Triangular numbers which are 8-almost primes.at n=12A076582
• a(1) = 1 and then smallest n-digit triangular number starting with the least significant digit of the previous term and not a multiple of 10.at n=5A077206
• Least number that requires n steps to reach 0 by repeated application of f: x -> abs(x - reverse(x)).at n=23A109891
• Triangular numbers for which the sum of the digits is a pentagonal number.at n=32A117305
• Triangle, read by rows, T(n, k) = binomial(n*binomial(n, floor((n-k)/2)), k).at n=38A157109
• a(n) = 1*3*5 + 3*5*7 + 5*7*9 + ... (n terms).at n=14A196506
• Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.at n=32A206025
• Consider numbers n = concat(x,y,z) such that the product x*y*z | n. Leading zeros in y and z allowed. Sequence lists numbers that admit different concatenations.at n=15A256518
• Refactorable triangular numbers.at n=23A272524
• Triangular numbers k such that psi(k) is a square, where psi(k) is the Dedekind psi function (A001615).at n=29A292064
• Number of nX7 0..1 arrays with every element equal to 0, 1, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.at n=7A303313
• Number of unordered pairs of distinct strict integer partitions of n.at n=33A366132