170185

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 39.at n=13A031627
• Pentagonal numbers for which the sum of the digits is also a pentagonal number.at n=34A117709
• Pentagonal numbers for which both the sum of the digits and the product of the digits are pentagonal numbers.at n=20A117711
• Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 0100-1100-0111 pattern in any orientation.at n=10A146585
• Number of different fixed (possibly) disconnected tetrominoes bounded tightly by an n X n square.at n=13A163434