123476589

Appears in sequences

• a(n) is the concatenation of the numbers appearing in row n of the lexicographically earliest prime pyramid (A051237).at n=8A187869
• a(1)=1; for n > 1, a(n) is the smallest number that is formed by arranging the decimal numbers "1", "2", ..., "n" in some order so that the sum of every pair of adjacent numbers "i" "j" is prime.at n=8A187871