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 A292239 A multiplicative encoding for the exponents of 2 obtained when using Shevelev's algorithm for computing A002326. 7
 2, 3, 10, 5, 28, 252, 840, 7, 88, 23760, 22, 330, 66528, 23760, 6652800, 11, 208, 468, 471744000, 390, 58240, 1872, 468, 163800, 93600, 39, 3736212480000, 39000, 17472, 94152554496000, 313841848320000, 13, 544, 7387354275840000, 146880, 84823200, 68, 36720, 12337920, 1079568000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(n) = prime(v(1)) * prime(v(2)) * ... * prime(v(k)), where prime(n) is the n-th prime (= A000040(n)) and v(1) .. v(k) are 2-adic valuations (not all necessarily distinct) of the iterated values obtained when running Shevelev's algorithm for computing A002326. See comments in A179680 and compare to A292265. LINKS Antti Karttunen, Table of n, a(n) for n = 0..1023 FORMULA For all n >= 0: A001222(a(n)) = A179382(1+n). A056239(a(n)) = A002326(n). MATHEMATICA a265[n_] := n/2^IntegerExponent[n, 2]; a[n_] := Module[{x, z, m}, x = 2 n + 1; z = Prime[IntegerExponent[1 + x, 2]]; m = a265[1 + x]; While[m != 1, z *= Prime[IntegerExponent[x + m, 2]]; m = a265[x + m]]; z]; Table[a[n], {n, 0, 39}] (* Jean-François Alcover, Oct 03 2017, translated from PARI *) PROG (PARI) A000265(n) = (n >> valuation(n, 2)); A292239(n) = { my(x = n+n+1, z = prime(valuation(1+x, 2)), m = A000265(1+x)); while(m!=1, z *= prime(valuation(x+m, 2)); m = A000265(x+m)); z; }; (Scheme) (define (A292239 n) (let ((x (+ n n 1))) (let loop ((z (A000040 (A007814 (+ 1 x)))) (k 1)) (let ((m (A000265 (+ x k)))) (if (= 1 m) z (loop (* z (A000040 (A007814 (+ x m)))) m)))))) CROSSREFS Cf. A000040, A000265, A002326, A007814, A179382, A179680, A292265 (a variant). Sequence in context: A175899 A064946 A078730 * A163767 A128531 A123167 Adjacent sequences:  A292236 A292237 A292238 * A292240 A292241 A292242 KEYWORD nonn AUTHOR Antti Karttunen, Oct 02 2017 STATUS approved

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Last modified August 15 09:12 EDT 2018. Contains 313756 sequences. (Running on oeis4.)