28680

Appears in sequences

• a(n) = Fibonacci(n) + n.at n=23A002062
• Even triangular numbers with prime indices.at n=27A034955
• a(n) = n^4 - (n-1)^4 + (n-2)^4 - ... 0^4.at n=15A062392
• Doubly hexagonal numbers.at n=8A063249
• a(n) = Sum_{d|n} d*Fibonacci(n/d).at n=22A066769
• Triangular numbers whose sum of prime factors (with repetition) is also triangular.at n=22A076169
• Triangular numbers which are 6-almost primes.at n=20A076580
• Numbers k such that 2^k - 1 is divisible by (k-1).at n=26A087965
• Structured truncated cubic numbers.at n=17A100152
• Triangular numbers with only even digits.at n=10A117978
• Triangular numbers p*(p+1)/2 with p prime such that 1+(number of prime factors of p+1) is prime.at n=23A144549
• Positive numbers n such that 2*120*n/(120+n) are integers.at n=39A162829
• a(n) = 1*3*5 + 3*5*7 + 5*7*9 + ... (n terms).at n=10A196506
• Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.at n=16A206025
• Least triangular number of the form p*triangular(n) where p is a prime number, or 0 if no such triangular number exists.at n=15A225789
• Numbers of the form k + wt(k) for exactly four distinct k, where wt(k) = A000120(k) is the binary weight of k.at n=3A227915
• Triangular numbers A000217 composed of only curved digits {0, 2, 3, 5, 6, 8, 9}.at n=45A247016
• Triangular numbers that are the product of a triangular number and a prime number.at n=43A253651
• 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=7A255917
• Construct a hollow square of 1's of side n and fill its interior with 0's to create a stack of n binary numbers. Express the sum of the stack in decimal.at n=11A269059