A372290 Numbers that occur in the odd bisection of A371094.
21, 45, 69, 93, 117, 141, 165, 189, 213, 237, 261, 285, 309, 333, 341, 357, 381, 405, 429, 453, 477, 501, 525, 549, 573, 597, 621, 645, 669, 693, 717, 725, 741, 765, 789, 813, 837, 861, 885, 909, 933, 957, 981, 1005, 1029, 1053, 1077, 1101, 1109, 1125, 1149, 1173, 1197, 1221, 1245, 1269, 1293, 1317, 1341, 1365, 1389
Offset: 1
Keywords
Examples
21 is present because A371094(1) = A371094(3) = 21. 45 is present because A371094(7) = 45. 87381 is present because A371094(85) = A371094(213) = A371094(7281) = A371094(14563) = 87381.
Links
- Antti Karttunen, Table of n, a(n) for n = 1..62122
Programs
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PARI
A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); }; isA372290(n) = if(!(n%2),0,forstep(k=1,n,2,if(A371094(k)==n,return(1))); (0));
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PARI
A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); }; A372290list(up_to_n) = { my(v=vector((1+up_to_n)/2), x, lista=List([])); forstep(k=1,up_to_n,2,x=A371094(k); if(x <= up_to_n, v[(x+1)/2]++)); for(i=1,(1+up_to_n)/2,if(v[i]>0, listput(lista,i+i-1))); Vec(lista); };
Comments