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 A049328 Numbers whose prime factors (taken with multiplicity) sum to 20. 0
 51, 91, 130, 154, 156, 220, 264, 297, 392, 441, 525, 560, 625, 630, 672, 750, 756, 800, 900, 960, 1024, 1080, 1152, 1215, 1296, 1458 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers whose prime factorization k = 2^i_1 * 3^i_2 * 5^i_3 * .. * 17^i_7 * 19^i_8 satisfies 2*i_1 + 3*i_2 + ... + 17*i_7 + 19*i_8 = 20. - N. J. A. Sloane, Jan 16 2019 LINKS Table of n, a(n) for n=1..26. EXAMPLE E.g. 51 = 3 * 17 and 3 + 17 = 20. 1024 = 2^10 and 10*2 = 20. MATHEMATICA pfs20Q[n_]:=Total[#[[1]]#[[2]]&/@FactorInteger[n]]==20; Select[Range[ 10000], pfs20Q] (* Harvey P. Dale, Jan 17 2019 *) CROSSREFS Numbers k such that A001414(k) = 20. Sequence in context: A253020 A351026 A020180 * A075894 A229274 A044140 Adjacent sequences: A049325 A049326 A049327 * A049329 A049330 A049331 KEYWORD fini,full,nonn AUTHOR Rawlyn Watson (rawlyn(AT)chplayers.freeserve.co.uk) EXTENSIONS Corrected by Frank Ellermann, Jun 07 2001 Further corrected by N. J. A. Sloane, Jan 16 2019 at the suggestion of Harvey P. Dale. STATUS approved

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Last modified June 23 07:16 EDT 2024. Contains 373629 sequences. (Running on oeis4.)