A383186 Inverse permutation to A383185 (square spiral numbers of king filling the two-dimensional grid always crossing the spiral's wall).

0, 5, 3, 1, 10, 25, 8, 6, 19, 17, 4, 15, 13, 2, 11, 30, 28, 26, 9, 24, 22, 7, 20, 18, 43, 41, 74, 16, 14, 37, 35, 33, 12, 31, 29, 60, 58, 27, 56, 54, 23, 52, 50, 48, 21, 46, 44, 42, 79, 77, 75, 40, 73, 38, 36, 69, 67, 34, 65, 32, 63, 61, 59, 100, 98, 147, 57, 55, 94, 53, 51, 90, 88, 49, 86

Offset: 0

Author

M. F. Hasler, May 12 2025

Keywords

• nonn

Links

• OEIS index to sequences related to permutations of the integers.

Crossrefs

Cf. A383185.

Programs

Python

def A383186(n):
    if not hasattr(A:=A383186, 'terms'): A.terms=[0]; A.N=1
    while len(t := A.terms) <= n:
       try: any(t.append(A383185.terms.index(k))for k in range(len(t), n+1))
       except: A.N = A.N*5//4+99; A383185(A.N)
    return A.terms[n]