203841

Appears in sequences

• Strong pseudoprimes to base 35.at n=31A020261
• Octagonal triangular numbers.at n=3A046183
• a(n) = the least integer that is polygonal in exactly n ways.at n=11A063778
• Triangular numbers obtained as a concatenation of successive terms of A081847.at n=20A082235
• Concatenation of triangular number k and its 10's complement is prime.at n=32A108970
• Triangular numbers for which the sum of the digits equals the sum of the digits of the next triangular number.at n=32A117511
• a(n) = (n-2)^4 - a(n-1) - a(n-2), with a(1) = a(2) = 0.at n=28A152729
• Least triangular n-gonal number greater than 1, or 0 if none exists.at n=41A188891
• Triangular numbers which have one or more occurrences of exactly six different digits.at n=27A241789
• Pseudoprimes to base 8 that are not squarefree.at n=26A243090
• Numbers m such that 3*m+1 and 8*m+1 are both squares.at n=6A245031
• Triangular numbers that are the sum of 2 consecutive terms of A130518.at n=9A247247
• Nonsquarefree numbers n = p_1^s_1...p_m^s_m (m > 1) such that (p_i^s_i - 1) | n-1 for all 0 < i <= m.at n=6A292815
• Pseudoprimes to base 10 that are not squarefree.at n=16A306449
• The area of the n-th convex honeycomb formed by spirals of incrementing strips of hexagons.at n=13A373081