64620

Appears in sequences

• Even triangular numbers with prime indices.at n=36A034955
• Numbers k such that pi(k) divides k.at n=41A057809
• Consider the sequence {b(m)} of nonprimes; sequence gives values of m where gcd{m, b(m)} increases.at n=41A058011
• Rearrangement of triangular numbers such that the sum of two consecutive terms is a palindrome.at n=45A082980
• Triangular numbers for which the number of divisors is also a triangular number.at n=21A116541
• Triangle, rows = inverse binomial transforms of A117938 columns.at n=39A117937
• Triangular numbers with only even digits.at n=13A117978
• Triangular numbers p*(p+1)/2 with p prime such that 1+(number of prime factors of p+1) is prime.at n=30A144549
• Triangular numbers t such that all the digits needed to write the consecutive triangular numbers from 0 to t fill exactly an equilateral triangle (no holes, no overlaps).at n=22A158030
• Numbers n such that pi(n) = (1/10)*n.at n=3A165689
• Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.at n=27A206025
• Number of (w,x,y,z) with all terms in {0,...,n} and odd range.at n=18A212890
• Triangular numbers n with digits d_1, d_2, ..., d_k such that d_1*(d_1+1)/2 + ... + d_k*(d_k+1)/2 is a triangular number.at n=42A254957
• Triangular numbers n such that each decimal digit of n is equal to the difference of at least two other digits of n.at n=11A255917
• Refactorable triangular numbers.at n=19A272524
• Lexicographically earliest sequence of nonnegative integers such that a(1)=3 and the sequence is p-periodic mod p for any p > 0.at n=21A284148
• The number of domino stacks with n dominos.at n=20A390209