A388030 Primitive terms of A388028.

6, 20, 28, 88, 104, 368, 464, 496, 650, 748, 836, 1216, 1376, 1430, 1888, 2205, 3230, 3465, 3904, 4030, 4070, 4672, 4712, 5830, 6232, 6370, 6536, 6790, 7436, 7912, 8128, 8415, 8968, 9656, 10184, 11132, 11552, 12285, 12950, 14008, 14552, 15368, 17050, 17272, 17816, 18585, 22496, 24448, 25690, 28035, 30310, 30592

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..13384

Index entries for sequences computed from indices in prime factorization.

Index entries for sequences related to binary expansion of n.

Index entries for sequences related to sigma(n).

Index entries for sequences where odd perfect numbers must occur, if they exist at all.

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
is_A388028(n) = { my(u=A003961(n)); ((u > 2*n) && bitor(u-2*n, u-sigma(n))==(u-2*n)); };
is_A388030(n) = if(!is_A388028(n), 0, fordiv(n, d, if(d<n && is_A388028(d), return(0))); (1));

Crossrefs

Subsequence of A388028.

Cf. A000396 (subsequence).

Sequence in context: A378530 A308710 A376874 * A389712 A388266 A388272

Adjacent sequences: A388027 A388028 A388029 * A388031 A388032 A388033

Keyword

nonn

Author

Antti Karttunen, Sep 15 2025

Status

approved