A372052 Where n appears in A370952, or -1 if n never appears there.

1, 4, 49, 2, 8, 24, 47, 22, 3, 20, 5, 18, 44, 16, 175, 14, 42, 12, 173, 10, 40, 6, 171, 88, 38, 335, 169, 86, 36, 333, 167, 84, 34, 331, 7, 82, 32, 329, 9, 80, 11, 327, 13, 78, 15, 325, 17, 76, 19, 323, 21, 74, 23, 321, 25, 72, 160, 319, 7468, 70, 158, 317, 25099

Offset: 1

Author

N. J. A. Sloane, Apr 17 2024

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A370952, A370975.

Programs

Python

from itertools import count
def A372052(n):
    a, aset = 1, {0,1}
    for p in count(3,2):
        if a == n:
            return p>>1
        for b in count(a%p,p):
            if b not in aset:
                aset.add(b)
                a = b
                break # Chai Wah Wu, Apr 17 2024

Python

# faster for initial segment of sequence
def A372052_gen(): # uses A370952_gen/imports from Chai Wah Wu in A370952
    adict, n = dict(), 1
    for i, v in enumerate(A370952_gen(), 1):
        if v >= n and v not in adict:
            adict[v] = i
            while n in adict:
                yield adict[n]; del adict[n]; n += 1
print(list(islice(A372052_gen(), 63))) # Michael S. Branicky, Apr 18 2024

Extensions

More terms from Chai Wah Wu, Apr 17 2024