A326612 Indices where A001175 (Pisano period) sets a new record value.

1, 2, 3, 5, 6, 10, 25, 30, 50, 98, 125, 150, 206, 243, 250, 490, 566, 590, 625, 750, 1030, 1046, 1094, 1154, 1214, 1226, 1250, 2450, 2738, 2830, 2846, 2894, 2906, 3086, 3125, 3750, 4802, 5534, 5594, 5606, 5666, 5714, 5770, 5834, 5906, 5990, 6070, 6130, 6250

Offset

1,2

Comments

Record values: 1, 3, 8, 20, 24, 60, 100, 120, 300, 336, 500, 600, 624, 648, 1500, 1680, 1704, 1740, 2500, 3000, ...

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000 (n = 1..1547 from Richard N. Smith)

Prog

(PARI) fibmod(n, m)=((Mod([1, 1; 1, 0], m))^n)[1, 2]
entryp(p)=my(k=p+[0, -1, 1, 1, -1][p%5+1], f=factor(k)); for(i=1, #f[, 1], for(j=1, f[i, 2], if((Mod([1, 1; 1, 0], p)^(k/f[i, 1]))[1, 2], break); k/=f[i, 1])); k
entry(n)=if(n==1, return(1)); my(f=factor(n), v); v=vector(#f~, i, if(f[i, 1]>1e14, entryp(f[i, 1]^f[i, 2]), entryp(f[i, 1])*f[i, 1]^(f[i, 2] - 1))); if(f[1, 1]==2&&f[1, 2]>1, v[1]=3<<max(f[1, 2]-2, 1)); lcm(v)
a(n)=if(n==1, return(1)); my(k=entry(n)); forstep(i=k, n^2, k, if(fibmod(i-1, n)==1, return(i)))
print1(r=1); for(n=2, 1000, if(a(n)>r, r=a(n); print1(", "n))) \\ after Charles R Greathouse IV in A001175

Crossrefs

Cf. A001175.

Sequence in context: A164523 A375734 A227305 * A240949 A033159 A366343

Adjacent sequences: A326609 A326610 A326611 * A326613 A326614 A326615

Keyword

nonn

Author

Richard N. Smith, Jul 14 2019

Status

approved