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A325097
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Heinz numbers of integer partitions whose distinct parts have no binary carries.
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11
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1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 19, 21, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 35, 36, 37, 38, 41, 42, 43, 47, 48, 49, 52, 53, 54, 56, 57, 58, 59, 61, 63, 64, 67, 69, 71, 72, 73, 74, 76, 79, 81, 83, 84, 86, 89, 95, 96, 97, 98, 99, 101
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OFFSET
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1,2
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COMMENTS
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A binary carry of two positive integers is an overlap of the positions of 1's in their reversed binary expansion.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1) * ... * prime(y_k), so these are numbers whose distinct prime indices have no binary carries.
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LINKS
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EXAMPLE
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Most small numbers are in the sequence, however the sequence of non-terms together with their prime indices begins:
10: {1,3}
15: {2,3}
20: {1,1,3}
22: {1,5}
30: {1,2,3}
34: {1,7}
39: {2,6}
40: {1,1,1,3}
44: {1,1,5}
45: {2,2,3}
46: {1,9}
50: {1,3,3}
51: {2,7}
55: {3,5}
60: {1,1,2,3}
62: {1,11}
65: {3,6}
66: {1,2,5}
68: {1,1,7}
70: {1,3,4}
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MATHEMATICA
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binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
stableQ[u_, Q_]:=!Apply[Or, Outer[#1=!=#2&&Q[#1, #2]&, u, u, 1], {0, 1}];
Select[Range[100], stableQ[PrimePi/@First/@FactorInteger[#], Intersection[binpos[#1], binpos[#2]]!={}&]&]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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