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A332229 Even numbers k such that A156552(k) is not a power of prime, and for which A323243(k) = sigma(A156552(k)) is congruent to 2 modulo 8. 2
290, 434, 550, 826, 858, 1394, 1798, 2254, 2418, 2546, 2950, 3094, 3910, 4150, 4382, 4930, 5590, 6138, 6358, 6390, 6710, 6966, 7514, 7546, 7622, 7658, 7990, 8550, 8798, 8906, 9230 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k for which A156552(k) is in A332228.

Sequence A005940(1+A332228(n)), n >= 1, sorted into ascending order.

LINKS

Table of n, a(n) for n=1..31.

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

PROG

(PARI)

A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552

isA332228(n) = ((n%2)&&!isprimepower(n)&&2==(sigma(n)%8));

isA332229(n) = isA332228(A156552(n));

(PARI)

v156552sigs = readvec("a156552.txt"); \\ Factorization file for A156552 prepared by Hans Havermann, available at https://oeis.org/A156552/a156552.txt

isA156552not_a_primepower(n) = if(n<=2, 0, my(prsig=v156552sigs[n]); length(prsig[1])>1);

A323243(n) = if(n<=2, n-1, my(prsig=v156552sigs[n], ps=prsig[1], es=prsig[2]); prod(i=1, #ps, ((ps[i]^(1+es[i]))-1)/(ps[i]-1)));

isA332229(n) = (!(n%2)&&isA156552not_a_primepower(n)&&(2==(A323243(n)%8)));

k=0; for(n=1, 10000, if(isA332229(n), k++; print1(n, ", ")));

CROSSREFS

Cf. A000203, A005940, A156552, A323243, A332225, A332228.

Subsequence of A324814.

Sequence in context: A186553 A075420 A075421 * A296055 A090839 A158255

Adjacent sequences:  A332226 A332227 A332228 * A332230 A332231 A332232

KEYWORD

nonn

AUTHOR

Antti Karttunen, Feb 13 2020

STATUS

approved

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Last modified October 25 21:15 EDT 2021. Contains 348256 sequences. (Running on oeis4.)