Oracle 18c

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create table t as

select date '2021-01-01' as dte, 1 as value from dual union all

select date '2021-01-02' as dte, 1 as value from dual union all

select date '2021-01-05' as dte, 1 as value from dual union all

select date '2021-01-07' as dte, 1 as value from dual union all

select date '2021-01-10' as dte, 1 as value from dual union all

select date '2021-01-12' as dte, 1 as value from dual union all

select date '2021-01-13' as dte, 1 as value from dual union all

select date '2021-01-16' as dte, 1 as value from dual union all

select date '2021-01-18' as dte, 1 as value from dual union all

select date '2021-01-22' as dte, 1 as value from dual union all

select date '2021-01-23' as dte, 1 as value from dual union all

select date '2021-01-30' as dte, 1 as value from dual

12 rows affected

with tt as (

select dte, value, row_number() over (order by dte) as seqnum

from t

cte (dte, value, seqnum, firstdte) as (

select tt.dte, tt.value, tt.seqnum, tt.dte

from tt

where seqnum = 1

union all

select tt.dte, tt.value, tt.seqnum,

(case when tt.dte < cte.firstdte + interval '7' day then cte.firstdte else tt.dte end)

from cte join

on tt.seqnum = cte.seqnum + 1

)

select firstdte, sum(value)

from cte

group by firstdte

order by firstdte