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A325094 Write n as a sum of distinct powers of 2, then take the primes of those powers of 2 and multiply them together. 8
1, 2, 3, 6, 7, 14, 21, 42, 19, 38, 57, 114, 133, 266, 399, 798, 53, 106, 159, 318, 371, 742, 1113, 2226, 1007, 2014, 3021, 6042, 7049, 14098, 21147, 42294, 131, 262, 393, 786, 917, 1834, 2751, 5502, 2489, 4978, 7467, 14934, 17423, 34846, 52269, 104538, 6943 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
The sorted sequence is A325093.
For example, 11 = 1 + 2 + 8, so a(11) = prime(1) * prime(2) * prime(8) = 114.
LINKS
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
6: {1,2}
7: {4}
14: {1,4}
21: {2,4}
42: {1,2,4}
19: {8}
38: {1,8}
57: {2,8}
114: {1,2,8}
133: {4,8}
266: {1,4,8}
399: {2,4,8}
798: {1,2,4,8}
53: {16}
106: {1,16}
159: {2,16}
318: {1,2,16}
371: {4,16}
MAPLE
P:= [seq(ithprime(2^i), i=0..10)]:
f:= proc(n) local L, i;
L:= convert(n, base, 2);
mul(P[i]^L[i], i=1..nops(L))
end proc:
map(f, [$0..100]); # Robert Israel, Mar 28 2019
MATHEMATICA
Table[Times@@MapIndexed[If[#1==0, 1, Prime[2^(#2[[1]]-1)]]&, Reverse[IntegerDigits[n, 2]]], {n, 0, 100}]
CROSSREFS
Sequence in context: A349756 A018748 A018258 * A191614 A018379 A245479
KEYWORD
nonn,look
AUTHOR
Gus Wiseman, Mar 27 2019
STATUS
approved

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Last modified May 21 17:21 EDT 2024. Contains 372738 sequences. (Running on oeis4.)