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A337543 Numbers that are in A337381, but that have no proper divisor in A337381. 6
6, 8, 9, 14, 15, 20, 21, 35, 44, 49, 50, 52, 68, 76, 92, 110, 124, 125, 130, 148, 172, 188, 190, 212, 230, 244, 275, 286, 292, 310, 325, 338, 356, 363, 425, 429, 452, 470, 475, 494, 507, 575, 598, 627, 663, 715, 741, 759, 775, 806, 845, 847, 874, 897, 925, 969, 1001, 1023, 1058, 1075, 1083, 1131, 1173, 1175, 1183, 1209 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k that are in A337381 [i.e., for which A003973(k) >= 2*A000203(k)], but none of whose proper divisors are in A337381.

LINKS

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

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

FORMULA

{k: 1==A337541(k)}.

PROG

(PARI)

A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };

A337541(n) = sumdiv(n, d, sigma(A003961(d))>=2*sigma(d));

isA337543(n) = (1==A337541(n));

CROSSREFS

Cf. A000203, A003961, A003973, A337381, A337383, A337541, A337542.

Cf. also A091191, A337372.

Sequence in context: A285275 A117096 A067812 * A047394 A184874 A085725

Adjacent sequences:  A337540 A337541 A337542 * A337544 A337545 A337546

KEYWORD

nonn

AUTHOR

Antti Karttunen, Aug 31 2020

STATUS

approved

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Last modified December 2 23:22 EST 2021. Contains 349445 sequences. (Running on oeis4.)