A387417 The largest proper divisor of the n-th primitive nondeficient number.

3, 10, 14, 35, 44, 52, 136, 152, 184, 232, 248, 275, 286, 325, 374, 418, 315, 592, 656, 688, 715, 752, 525, 848, 935, 944, 976, 1001, 1045, 735, 1105, 1235, 1265, 1292, 1495, 1564, 1595, 1615, 1705, 1155, 1748, 1885, 1972, 2015, 2035, 1365, 2108, 2144, 2204, 2255, 2272, 2336, 2356, 2365

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Formula

a(n) = A032742(A006039(n)).

a(n) = A387717(A006039(n)).

Prog

(PARI)
A032742(n) = if(1==n, n, n/vecmin(factor(n)[, 1]));
A341619(n) = if(sigma(n)<(2*n), 0, fordiv(n, d, if((d<n)&&(sigma(d) >= 2*d), return(0))); (1));
for(n=1, 2^14, if(A341619(n), print1(A032742(n), ", ")));

Crossrefs

Cf. A006039, A032742, A387717.

Cf. also A378741.

Sequence in context: A023866 A024593 A128930 * A328091 A048852 A226101

Adjacent sequences: A387414 A387415 A387416 * A387418 A387419 A387420

Keyword

nonn

Author

Antti Karttunen, Sep 11 2025

Status

approved