A394895 After 1, numbers k such that A006530(A003415(k)) is equal to A006530(A276085(k)).

1, 2, 4, 8, 10, 12, 15, 16, 27, 28, 32, 35, 63, 64, 100, 128, 135, 187, 189, 243, 256, 297, 392, 480, 500, 512, 686, 729, 972, 1000, 1024, 1280, 1350, 1375, 1568, 1728, 1890, 2048, 2187, 2352, 2700, 2835, 2975, 3125, 3432, 3584, 3969, 4032, 4096, 5005, 5096, 5940, 7776, 8192, 8232, 8281, 8704, 9317, 10000, 12005

Offset

1,2

Comments

Intersection with A048103 is: 1, 2, 10, 15, 35, 63, 187, 686, 1375, 2975, 5005, 8281, 9317, 12005, 14365, 29887, 43681, 563255, 606375, 753571, 805255, ...

Links

Antti Karttunen, Table of n, a(n) for n = 1..157

Formula

{k such that either k = 1, or A395042(k) = A395052(k)}.

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A276085(n) = { my(f=factor(n)); sum(k=1, #f~, f[k, 2]*prod(i=1, primepi(f[k, 1]-1), prime(i))); };
is_A394895(n) = if(n<=2, 1, if(n>2 && isprime(n), 0, my(ad = A003415(n), f = factor(ad), gpfad = vecmax(f[, 1]), x = A276085(n)); if(x % gpfad, 0, forprime(p=2, gpfad, x /= (p^valuation(x, p)))); (1==x)));

Crossrefs

Cf. A003415, A006530, A048103, A276085, A395042, A395052.

Cf. A369650 (subsequence).

Cf. also A373490.

Sequence in context: A032494 A125953 A373490 * A308357 A047464 A189786

Adjacent sequences: A394892 A394893 A394894 * A394896 A394897 A394898

Keyword

nonn

Author

Antti Karttunen, Apr 15 2026

Status

approved