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 A261604 a(1)=0. For n>1, a(n) = smallest number > a(n-1) such that, for all m,r
 0, 1, 3, 4, 5, 6, 7, 8, 11, 12, 13, 14, 15, 19, 20, 21, 22, 23, 24, 27, 28, 29, 30, 31, 33, 35, 38, 39, 40, 42, 43, 44, 46, 47, 48, 51, 53, 54, 55, 56, 57, 59, 60, 62, 63, 66, 67, 68, 69, 70, 71, 75, 76, 77, 78, 79, 81, 82, 83, 84, 86, 87, 88 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 Anders Hellström, Ruby program FORMULA a(n) ~ n, and in particular a(n) = n + O(n/sqrt(log n)). I do not know if this bound is tight. - Charles R Greathouse IV, Sep 01 2015 PROG (PARI) issumsq(n, r, s)=(r^2)+(s^2)==n first(m)=my(v=vector(m), x, r, n, s); v[1]=0; for(n=2, m, v[n]=v[n-1]+1; until(x==1, for(r=1, n-1, for(s=1, n-1, if(issumsq(v[n], v[r], v[s]), v[n]++; x=0; break(2), x=1))))); v; (PARI) isA022544(n)=if(n%4==3, return(1)); my(f=factor(n)); for(i=1, #f~, if(f[i, 1]%4==3 && f[i, 2]%2, return(1))); 0 search(v, x)=my(t=setsearch(v, x)); if(t, t, setsearch(v, x, 1)) list(lim)=my(v=List([0, 1]), t); for(n=3, lim, if(isA022544(n), listput(v, n); next); for(j=search(v, sqrtint((n-1)\2)+1), search(v, sqrtint(n)), if(issquare(n-v[j]^2, &t) && setsearch(v, t), next(2))); listput(v, n)); Set(v) \\ Charles R Greathouse IV, Sep 01 2015 CROSSREFS A022544 is a subsequence. Cf. A026468, A026466, A026467, A026469, A026470. Sequence in context: A273664 A332416 A047563 * A120561 A051016 A044951 Adjacent sequences:  A261601 A261602 A261603 * A261605 A261606 A261607 KEYWORD nonn AUTHOR Anders Hellström, Aug 25 2015 STATUS approved

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Last modified June 22 13:46 EDT 2021. Contains 345380 sequences. (Running on oeis4.)