31217

Appears in sequences

• a(n) is the concatenation of n and 7n.at n=30A009441
• a(n) is the smallest number such that there are exactly n numbers k (including a(n) itself) such that U(k) is isomorphic to U(a(n)) (or 0 if no such number exists). Here U(k) is the multiplicative group of integers modulo k.at n=39A303712
• Number of multiples of n which have only distinct and nonzero digits in base 10.at n=28A328287
• On a spirally numbered square grid, with labels starting at 1, this is the number of steps that an (n,n+1) leaper makes before getting trapped, or -1 if it never gets trapped.at n=21A343178
• Concatenate the terms of A027750 (omitting spaces and commas), chop into blocks of length 5, then omit any leading zeros.at n=31A362446