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 A337344 Odd numbers k such that A064989(sigma(k)) >= k. 1
 1, 9, 25, 225, 289, 729, 1681, 2401, 2601, 3481, 5041, 6561, 7225, 7921, 10201, 15129, 15625, 17161, 18225, 19881, 21609, 27889, 28561, 29929, 31329, 35721, 42025, 45369, 59049, 60025, 62001, 65025, 71289, 83521, 85849, 87025, 88209, 91809, 114921, 123201, 126025, 130321, 140625, 146689, 154449, 164025, 172225 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Applying A064989 to these terms and sorting into ascending order gives A326182. Conversely, this sequence is obtained when the sequence b(n) = A003961(A326182(n)) is sorted into ascending order. Not all terms are squares. For example, 12121028325 = A003961(A326183(1)) = 3^6 * 5^2 * 7^4 * 277 is also term, and this is true for all terms of A326183 similarly prime shifted. Interestingly, for n = 1..24, A003961(A326183(n)) is a term of A228058. LINKS PROG (PARI) A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)}; isA337344(n) = ((n%2)&&(A064989(sigma(n))>=n)); CROSSREFS Odd terms of A337343. Cf. A000203, A003961, A064989, A228058, A326042, A326182, A326183. Sequence in context: A018929 A051515 A328714 * A053929 A014760 A013397 Adjacent sequences:  A337341 A337342 A337343 * A337345 A337346 A337347 KEYWORD nonn AUTHOR Antti Karttunen, Aug 26 2020 STATUS approved

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Last modified October 18 03:25 EDT 2021. Contains 348065 sequences. (Running on oeis4.)