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 A332223 a(1) = 1, and for n > 1, a(n) = A005940(1+sigma(A156552(n))). 5
 1, 2, 4, 5, 8, 9, 16, 7, 25, 18, 32, 25, 64, 21, 21, 49, 128, 27, 256, 35, 40, 121, 512, 49, 125, 385, 49, 121, 1024, 13, 2048, 13, 225, 1573, 105, 77, 4096, 57, 187, 343, 8192, 63, 16384, 65, 55, 4693, 32768, 121, 625, 32, 15625, 85, 65536, 81, 180, 91, 253, 9945, 131072, 175, 262144, 508079, 625, 847, 729, 169, 524288, 2057, 2601, 105, 1048576 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 (computed using Hans Havermann's factorization of A156552) FORMULA For n > 1, a(n) = A005940(1+A000203(A156552(n))) = A005940(1+A323243(n)). a(A324201(n)) = A003961(A324201(n)). PROG (PARI) A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940 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 A332223(n) = if(1==n, n, A005940(1+sigma(A156552(n)))); CROSSREFS Cf. A000203, A003961, A005940, A027687, A156552, A246277, A323243, A324201, A332224, A332225. Cf. also A332222. Sequence in context: A195364 A279793 A305076 * A269361 A200947 A333256 Adjacent sequences:  A332220 A332221 A332222 * A332224 A332225 A332226 KEYWORD nonn AUTHOR Antti Karttunen, Feb 12 2020 STATUS approved

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Last modified May 26 17:02 EDT 2020. Contains 334630 sequences. (Running on oeis4.)