A341869 For any k, the cumulative sum of the terms a(1) + a(2) + a(3) + ... + a(k) and the cumulative sum of their digits so far are odd. This is the lexicographically earliest sequence of distinct terms > 0 with this property.
1, 2, 4, 6, 8, 20, 22, 24, 26, 28, 40, 42, 44, 46, 48, 60, 62, 64, 66, 68, 80, 82, 84, 86, 88, 110, 112, 114, 116, 118, 130, 132, 134, 136, 138, 150, 152, 154, 156, 158, 170, 172, 174, 176, 178, 190, 192, 194, 196, 198, 200, 202, 204, 206, 208, 220, 222, 224, 226, 228, 240, 242, 244, 246, 248
Offset: 1
Examples
Sequence = 1,2,4, 6, 8,20,22,24, 26, 28, 40, 42, 44 ... Cumulative sum of terms = 1 3 7 13 21 41 63 87 113 141 181 223 267 ... Cumulative sum of digits = 1 3 7 13 21 23 27 33 41 51 55 61 69 ...
Crossrefs
Cf. A179082.
Programs
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Mathematica
a[1]=1;a[n_]:=a[n]=Block[{k=1},While[MemberQ[q=Array[a,n-1],k]||EvenQ@Total[s=Join[q,{k}]]||EvenQ@Total[Flatten[IntegerDigits/@s]],k++];k];Array[a,65] (* Giorgos Kalogeropoulos, May 11 2022 *)
Comments