17955

Appears in sequences

• a(n) = (4*n+1)*(4*n+3).at n=33A001539
• Odd abundant numbers (odd numbers m whose sum of divisors exceeds 2m).at n=37A005231
• Solution to a Diophantine equation: each term is a triangular number and each term + 1 is a square.at n=6A006454
• Geometric mean of phi(n) and sigma(n) is an integer, n odd.at n=32A015705
• Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= (n+2)/3.at n=21A048073
• Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= (n+3)/3.at n=21A048084
• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=20A050534
• Indices of primes in sequence defined by A(0) = 11, A(n) = 10*A(n-1) + 21 for n > 0.at n=12A056244
• a(n)= product of all odd composite numbers between n-th prime and (n+1)-st prime.at n=31A061215
• Triangular numbers whose index is a multiple of the sum of their digits.at n=32A067520
• Triangular numbers which are products of triangular numbers larger than 1.at n=21A068143
• Triangular numbers of the form 21*k.at n=36A069499
• Pair the odd numbers such that the k-th pair is (r, r+2k) where r is the smallest odd number not included earlier: (1, 3), (5, 9), (7, 13), (11, 19), (15, 25), (17, 29), (21, 35), (23, 39), (27, 45), ... This is the sequence of the product of the members of pairs.at n=32A075320
• Triangular numbers which are 6-almost primes.at n=14A076580
• a(n) = smallest number which can be expressed as sum of d consecutive positive integers in exactly n ways (where d>0 is a divisor of the number).at n=18A082637
• Smallest triangular number > 1 and == 1 (mod prime(n)).at n=42A087397
• ((Cumulative sum A000045) + (A000079)) - A092176.at n=15A093304
• a(n) = binomial(n+2,2)*binomial(n+6,2).at n=13A104473
• Odd terms of A059756.at n=15A111042
• Number of monic irreducible polynomials of degree n in GF(7)[x,y].at n=2A115469