397575

Appears in sequences

• Group the triangular numbers so that the n-th group sum is a multiple of n. 1, (3, 6, 10, 15), (21), (28), (36, 45, 55, 66, 78), (91, 105, 120, 136, 153, 171, 190), ... Sequence contains the group sums.at n=24A114031
• Odd numbers n such that 2n/sigma(n) - 1 = 1/x for some positive integer x.at n=36A222263
• Numbers whose abundancy, sigma(n)/n, is 1024/513.at n=0A230148
• Terms of A222263 such that 2n/sigma(n) - 1 = 1/2^k, for some integer k.at n=12A230166
• Smallest b > 1 such that b^(p-1) == 1 (mod p^4) for p = prime(n).at n=17A353937